5,307 research outputs found
Synthetic Data Generation using Benerator Tool
Datasets of different characteristics are needed by the research community
for experimental purposes. However, real data may be difficult to obtain due to
privacy concerns. Moreover, real data may not meet specific characteristics
which are needed to verify new approaches under certain conditions. Given these
limitations, the use of synthetic data is a viable alternative to complement
the real data. In this report, we describe the process followed to generate
synthetic data using Benerator, a publicly available tool. The results show
that the synthetic data preserves a high level of accuracy compared to the
original data. The generated datasets correspond to microdata containing
records with social, economic and demographic data which mimics the
distribution of aggregated statistics from the 2011 Irish Census data.Comment: 12 pages, 5 figures, 10 reference
Ontology-Based Quality Evaluation of Value Generalization Hierarchies for Data Anonymization
In privacy-preserving data publishing, approaches using Value Generalization
Hierarchies (VGHs) form an important class of anonymization algorithms. VGHs
play a key role in the utility of published datasets as they dictate how the
anonymization of the data occurs. For categorical attributes, it is imperative
to preserve the semantics of the original data in order to achieve a higher
utility. Despite this, semantics have not being formally considered in the
specification of VGHs. Moreover, there are no methods that allow the users to
assess the quality of their VGH. In this paper, we propose a measurement
scheme, based on ontologies, to quantitatively evaluate the quality of VGHs, in
terms of semantic consistency and taxonomic organization, with the aim of
producing higher-quality anonymizations. We demonstrate, through a case study,
how our evaluation scheme can be used to compare the quality of multiple VGHs
and can help to identify faulty VGHs.Comment: 18 pages, 7 figures, presented in the Privacy in Statistical
Databases Conference 2014 (Ibiza, Spain
A Precipitation Model and Experimental Correlation with Various Properties of Pentaerythritol Tetranitrate
A continuous precipitation method for the preparation of crystalline pentaerythritol tetranitrate (PETN) has been developed. The process involves the precipitation of PETN from an acetone solution by the addition of water in a static mixer. The principal independent variable is the ratio, R, of the acetone-PETN solution flow rate to the flow rate of water.
A mathematical model based on dispersed plug-flow equations adequately represents the physical process. The relationships developed can be used to predict particle size distributions, two explosion properties of PETN, and estimate the effective kinetics involved in the precipitation process. The mass-weighted mean particle size, L, of the precipitated PETN is a linear function of R. The initial nucleation and growth rates are exponentially decaying functions of R. The nucleation exponent is 3.75 ± 0.05; the growth rate exponent is 1.56 * 0.02. The value of the diffusion parameter, Pe, is 51 ± 1. Experimentally determined PETN initiation-threshold voltages can be expressed as a second degree polynomial in L, with a minimum at about 50 μm. Observed PETN explosion transit times follow a third degree polynomial in L, increasing with increasing particle size
Plasmon-Emitter Interactions at the Nanoscale
Plasmon-emitter interactions are of paramount importance in modern
nanoplasmonics and are generally maximal at short emitter-surface separations.
However, when the separation falls below 10-20 nm, the classical theory
progressively deteriorates due to its neglect of quantum mechanical effects
such as nonlocality, electronic spill-out, and Landau damping. Here, we show
how this neglect can be remedied by presenting a unified theoretical treatment
of mesoscopic electrodynamics grounded on the framework of Feibelman
-parameters. Crucially, our technique naturally incorporates nonclassical
resonance shifts and surface-enabled Landau damping - a nonlocal damping effect
- which have a dramatic impact on the amplitude and spectral distribution of
plasmon-emitter interactions. We consider a broad array of plasmon-emitter
interactions ranging from dipolar and multipolar spontaneous emission
enhancement, to plasmon-assisted energy transfer and enhancement of two-photon
transitions. The formalism presented here gives a complete account of both
plasmons and plasmon-emitter interactions at the nanoscale, constituting a
simple yet rigorous and general platform to incorporate nonclassical effects in
plasmon-empowered nanophotonic phenomena.Comment: 12 pages, 6 figure
A Symplectic Integrator for Hill's Equations
Hill's equations are an approximation that is useful in a number of areas of
astrophysics including planetary rings and planetesimal disks. We derive a
symplectic method for integrating Hill's equations based on a generalized
leapfrog. This method is implemented in the parallel N-body code, PKDGRAV and
tested on some simple orbits. The method demonstrates a lack of secular changes
in orbital elements, making it a very useful technique for integrating Hill's
equations over many dynamical times. Furthermore, the method allows for
efficient collision searching using linear extrapolation of particle positions.Comment: 15 pages, 2 figures; minor revisions; accepted for publication in the
Astronomical Journa
- …