1,149,114 research outputs found
Interactive Constrained Association Rule Mining
We investigate ways to support interactive mining sessions, in the setting of
association rule mining. In such sessions, users specify conditions (queries)
on the associations to be generated. Our approach is a combination of the
integration of querying conditions inside the mining phase, and the incremental
querying of already generated associations. We present several concrete
algorithms and compare their performance.Comment: A preliminary report on this work was presented at the Second
International Conference on Knowledge Discovery and Data Mining (DaWaK 2000
A General Framework for Flexible Multi-Cue Photometric Point Cloud Registration
The ability to build maps is a key functionality for the majority of mobile
robots. A central ingredient to most mapping systems is the registration or
alignment of the recorded sensor data. In this paper, we present a general
methodology for photometric registration that can deal with multiple different
cues. We provide examples for registering RGBD as well as 3D LIDAR data. In
contrast to popular point cloud registration approaches such as ICP our method
does not rely on explicit data association and exploits multiple modalities
such as raw range and image data streams. Color, depth, and normal information
are handled in an uniform manner and the registration is obtained by minimizing
the pixel-wise difference between two multi-channel images. We developed a
flexible and general framework and implemented our approach inside that
framework. We also released our implementation as open source C++ code. The
experiments show that our approach allows for an accurate registration of the
sensor data without requiring an explicit data association or model-specific
adaptations to datasets or sensors. Our approach exploits the different cues in
a natural and consistent way and the registration can be done at framerate for
a typical range or imaging sensor.Comment: 8 page
NETWORK SECURITY IN CRYPTOGRAPHY
Association Security and Cryptography is a plan to guarantee association and data transmission over far off association. Data Security is the central piece of secure data transmission over sensitive association. Association security remembers the endorsement of permission to data for an association, which is obliged by the association executive. Customers pick or are consigned an ID and mystery state or other affirming information that grants them induction to information and ventures inside their capacity. Association security covers an arrangement of PC associations, both public and private, that are used in customary positions driving trades and exchanges among associations, government workplaces and individuals. Associations can be private, for instance, inside an association, and others which might be accessible to network. Association security is locked in with affiliations, adventures, and various kinds of establishments. Aggravation receptive association (DTN) progressions are getting victorious plans that award center points to talk with each other in these absurd frameworks organization conditions. Consistently, when there is no restriction to-end relationship between a source and a goal pair, the messages from the source center point may require keeping things under control in the center points for a lot of time impending the affiliation would be in the end set up. The possibility of value based encryption (ABE) is a capable technique that fulfills the requirements for secure data recuperation in DTNs. Especially, Cipher text-Policy ABE (CP-ABE) gives a versatile technique for encoding data with the ultimate objective that the scramble or portrays the property set that the unscramble or needs to need to translate the code text. Thusly, divergent customers are allowable to unscramble different pieces of data per the security system
XMM-Newton observations of a superbubble in N 158 in the LMC
Aims: We study the diffuse X-ray emission observed in the field of view of
the pulsar B 0540-69 in the Large Magellanic Cloud (LMC) by XMM-Newton. We want
to understand the nature of this soft diffuse emission, which coincides with
the superbubble in the HII region N 158, and improve our understanding of the
evolution of superbubbles. Methods: We analyse the XMM-Newton spectra of the
diffuse emission. Using the parameters obtained from the spectral fit, we
perform calculations of the evolution of the superbubble. The mass loss and
energy input rates are based on the initial mass function (IMF) of the observed
OB association inside the superbubble. Results: The analysis of the spectra
shows that the soft X-ray emission arises from hot shocked gas surrounded by a
thin shell of cooler, ionised gas. We show that the stellar winds alone cannot
account for the energy inside the superbubble, but the energy release of 2 - 3
supernova explosions in the past ~1 Myr provides a possible explanation.
Conclusions: The combination of high sensitivity X-ray data, allowing spectral
analysis, and analytical models for superbubbles bears the potential to reveal
the evolutionary state of interstellar bubbles, if the stellar content is
known.Comment: 7 pages. Accepted for publication in A&
Crossover soft-SAFT modelling of the CO2+NO2/N2O4 mixture
Accurate thermo-physical properties are mandatory for all industrial applications. However, experimental data are often scarce and models are needed for the estimation of properties. Such is the case in supercritical processes like the selective oxidation of vegetal macromolecules in mixture NO2/N2O4 – supercritical CO2 aiming at producing body-degradable polymers readily usable for inside body surgery. The so-called crossover soft-SAFT equation of state is used to model the pure compounds and the mixture. The quadrupolar effect is explicitly considered when modeling carbon dioxide, obtaining excellent agreement for the whole phase equilibrium diagram. NO2 is modeled as a self associating molecule with a single association site. Finally, CO2 and NO2 pure compound parameters are used to predict the vapor – liquid coexistence of the CO2 + NO2 / N2O4 mixture at different temperatures. Experimental pressure – CO2 mass fraction isotherms recently measured are used for comparison. Good agreement is obtained with the use of a unique binary parameter, independent of thermodynamic conditions, although more experimental data would be useful to conclude about the accuracy of the calculation
The Stellar Composition of the Star Formation Region CMa R1. II. Spectroscopic and Photometric Observations of 9 Young Stars
We present new high and low resolution spectroscopic and photometric data of
nine members of the young association CMa R1. All the stars have circumstellar
dust at some distance as could be expected from their association with
reflection nebulosity. Four stars (HD 52721, HD 53367, LkHalpha 220 and
LkHalpha 218) show Halpha emission and we argue that they are Herbig Be stars
with discs. Our photometric and spectroscopic observations on these stars
reveal new characteristics of their variability. We present first
interpretations of the variability of HD 52721, HD 53367 and the two LkHalpha
stars in terms of a partially eclipsing binary, a magnetic activity cycle and
circumstellar dust variations, respectively. The remaining five stars show no
clear indications of Halpha emission in their spectra, although their spectral
types and ages are comparable with those of HD 52721 and HD 53367. This
indicates that the presence of a disc around a star in CMa R1 may depend on the
environment of the star. In particular we find that all Halpha emission stars
are located at or outside the arc-shaped border of the H II region, which
suggests that the stars inside the arc have lost their discs through
evaporation by UV photons from nearby O stars, or from the nearby (< 25 pc)
supernova, about 1 Myr ago.Comment: 17 pages, 13 figures, accepted by MNRA
Spitzer/MIPS Observations of Stars in the Beta Pictoris Moving Group
We present Multiband Imaging Photometer for Spitzer (MIPS) observations at 24
and 70 microns for 30 stars, and at 160 microns for a subset of 12 stars, in
the nearby (~30 pc), young (~12 Myr) Beta Pictoris Moving Group (BPMG). In
several cases, the new MIPS measurements resolve source confusion and
background contamination issues in the IRAS data for this sample. We find that
7 members have 24 micron excesses, implying a debris disk fraction of 23%, and
that at least 11 have 70 micron excesses (disk fraction of >=37%). Five disks
are detected at 160 microns (out of a biased sample of 12 stars observed), with
a range of 160/70 flux ratios. The disk fraction at 24 and 70 microns, and the
size of the excesses measured at each wavelength, are both consistent with an
"inside-out" infrared excess decrease with time, wherein the shorter-wavelength
excesses disappear before longer-wavelength excesses, and consistent with the
overall decrease of infrared excess frequency with stellar age, as seen in
Spitzer studies of other young stellar groups. Assuming that the infrared
excesses are entirely due to circumstellar disks, we characterize the disk
properties using simple models and fractional infrared luminosities. Optically
thick disks, seen in the younger TW Hya and eta Cha associations, are entirely
absent in the BPMG.
Additional flux density measurements at 24 and 70 microns are reported for
nine Tucanae-Horologium Association member stars. Since this is <20% of the
association membership, limited analysis on the complete disk fraction of this
association is possible.Comment: Accepted for Ap
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