446 research outputs found
Comparison between Finite-Difference Time-Domain Method and Experimental Results for Femtosecond Laser Pulse Propagation
Human Activity Recognition System Including Smartphone Position
AbstractThe data gathered by acceleration sensors in smartphones gives different results depending on the location of the smartphone. In this paper, a human activity recognition system was proposed, including the smartphone's position. This system can recognize not only the activity of a person, but also the location of the smartphone. HOG (Histograms of Oriented Gradients) were used to extract features of the acceleration data, because the waveform of the acceleration data is very complex. Then, a strong classifier was obtained using a learning algorithm of Real AdaBoost based on the position of possession smartphone and acceleration sensor data. It also improves the recognition rate by analyzing the acceleration data. The effectiveness of the activity recognition system was shown by the experiment
A survey of T Tauri stars with AKARI toward the Taurus-Auriga region
Aims: We search new T Tauri star (TTS) candidates with the mid-infrared (MIR)
part of the AKARI All-Sky Survey at 9 and 18 um wavelengths. Methods: We used
the point source catalogue (PSC), obtained by the Infrared Camera (IRC) on
board AKARI. We combined the 2MASS PSC and the 3rd version of the USNO CCD
Astrograph Catalogue (UCAC) with the AKARI IRC-PSC, and surveyed 517 known TTSs
over a 1800-square-degree part of the Taurus-Auriga region to find criteria to
extract TTSs. We considered asymptotic giant branch (AGB) stars, post-AGB
stars, Planetary Nebulae (PNe), and galaxies, which have similar MIR colours,
to separate TTSs from these sources. Results: Of the 517 known TTSs, we
detected 133 sources with AKARI. Based on the colour-colour and
colour-magnitude diagrams made from the AKARI, 2MASS, and UCAC surveys, we
propose the criteria to extract TTS candidates from the AKARI All-Sky data. On
the basis of our criteria, we selected 176/14725 AKARI sources as TTS
candidates which are located around the Taurus-Auriga region. Comparing these
sources with SIMBAD, there are 148 previously identified sources including 115
Young Stellar Objects (YSOs), and 28 unidentified sources. Conclusions: Based
on SIMBAD identifications, we take the TTS-identification probability using our
criteria to be ~75 %. We find 28 TTS candidates, of which we expect 21 to be
confirmed once follow-up observations can be obtained. Although the probability
of ~75 % is not so high, it is affected by the completeness of the SIMBAD
database, and we can search for TTSs over the whole sky, over all star forming
regions.Comment: 12 pages, 9 figures, accepted for publication in A&
AKARI IRC 2.5-5 um Spectroscopy of Infrared Galaxies over a Wide Luminosity Range
We present the result of a systematic infrared 2.5-5 um spectroscopic study
of 22 nearby infrared galaxies over a wide infrared luminosity range (10 <
log(L_IR / Lsun) < 13) obtained from AKARI Infrared Camera (IRC). The unique
band of the AKARI IRC spectroscopy enables us to access both the 3.3 um
polycyclic aromatic hydrocarbon (PAH) emission feature from star forming
activity and the continuum of torus-dust emission heated by an active galactic
nucleus (AGN). Applying our AGN diagnostics to the AKARI spectra, we discover
14 buried AGNs. The large fraction of buried AGNs suggests that AGN activity
behind the dust is almost ubiquitous in ultra-/luminous infrared galaxies
(U/LIRGs). We also find that both the fraction and energy contribution of
buried AGNs increase with infrared luminosity from 10 < log(L_IR / Lsun) < 13,
including normal infrared galaxies with log (L_IR / Lsun) < 11. The energy
contribution from AGNs in the total infrared luminosity is only ~7% in LIRGs
and ~20% in ULIRGs, suggesting that the majority of the infrared luminosity
originates from starburst activity. Using the PAH emission, we investigate the
luminosity relation between star formation and AGN. We find that these infrared
galaxies exhibit higher star formation rates than optically selected Seyfert
galaxies with the same AGN luminosities, implying that infrared galaxies could
be an early evolutionary phase of AGN.Comment: 13 pages, 8 figures, accepted for publication in Ap
Improved Bounds on Information Dissemination by Manhattan Random Waypoint Model
With the popularity of portable wireless devices it is important to model and
predict how information or contagions spread by natural human mobility -- for
understanding the spreading of deadly infectious diseases and for improving
delay tolerant communication schemes. Formally, we model this problem by
considering moving agents, where each agent initially carries a
\emph{distinct} bit of information. When two agents are at the same location or
in close proximity to one another, they share all their information with each
other. We would like to know the time it takes until all bits of information
reach all agents, called the \textit{flood time}, and how it depends on the way
agents move, the size and shape of the network and the number of agents moving
in the network.
We provide rigorous analysis for the \MRWP model (which takes paths with
minimum number of turns), a convenient model used previously to analyze mobile
agents, and find that with high probability the flood time is bounded by
, where agents move on an
grid. In addition to extensive simulations, we use a data set of
taxi trajectories to show that our method can successfully predict flood times
in both experimental settings and the real world.Comment: 10 pages, ACM SIGSPATIAL 2018, Seattle, U
Design Live Load Factor Calibration for Michigan Highway Bridges
In this study, a reliability-based calibration of live load factors for bridge design specific to the State of Michigan was conducted. Two years of high frequency WIM data from 20 representative state-wide sites were analyzed, and load effects were generated for bridge spans from 6 to 122 m (20 to 400 ft), considering simple and continuous moments and shears, as well as single lane and two lane effects. Seventy-five year statistics for maximum live load were then estimated with probabilistic projection. Bridge girders considered for the calibration included composite steel, prestressed concrete, side-by-side and spread box beams, as well as special long span structural members. In some cases, it was found that Michigan load effects are greater than those previously assumed, often requiring higher load factors than in current use. Moreover, significant variation in the required load factor was found, potentially resulting significant inconsistencies in reliability if a single load factor is used for the design of all bridge types and load effects considered
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