682 research outputs found
Suzaku X-Ray Observation of the Dwarf Nova Z Camelopardalis at the Onset of an Optical Outburst
We present the result of a Suzaku X-ray spectroscopic observation of the
dwarf nova Z Camelopardalis, which was conducted by chance at the onset of an
optical outburst. We used the X-ray Imaging Spectrometer (a 38 ks exposure) and
the Hard X-ray Detector (34 ks) to obtain a 0.35-40 keV spectrum
simultaneously. Spectral characteristics suggest that the source was in the
X-ray quiescent state despite being in the rising phase of an outburst in the
optical band. The spectrum shows a clear signature of circumstellar absorption
in excess of interstellar absorption and the reprocessed emission features of
Fe fluorescence and Compton scattering. The extra absorption is explained due
to partial coverage by either neutral or ionized matter. We found a spectral
change during the observation, which is attributable only to the change in the
circumstellar absorption. Such an X-ray spectral variation is reported for the
first time in dwarf novae. We speculate that the variation in the circumstellar
absorption is interpreted as a time-varying disk wind or geometrically flaring
disk around the white dwarf during the propagation of a heat wave inward along
the accretion disk at the beginning of the outburst, in which optical outburst
and X-ray quiescent states co-exist.Comment: 10 pages, 9 figures, accepted for publication in PAS
Adaptive Sensing Based on Profiles for Sensor Systems
This paper proposes a profile-based sensing framework for adaptive sensor systems based on models that relate possibly heterogeneous sensor data and profiles generated by the models to detect events. With these concepts, three phases for building the sensor systems are extracted from two examples: a combustion control sensor system for an automobile engine, and a sensor system for home security. The three phases are: modeling, profiling, and managing trade-offs. Designing and building a sensor system involves mapping the signals to a model to achieve a given mission
Spatially Inhomogeneous Superconducting State near in UPdAl
We have performed Al-NMR measurements on single-crystalline
UPdAl with the field parallel to the axis to investigate the
superconducting (SC) properties near the upper critical field of
superconductivity . The broadening of the NMR linewidth below 14~K
indicates the appearance of the internal field at the Al site, which originates
from the antiferromagnetically ordered moments of U 5 electrons. In the SC
state well below = 3.4~T, the broadening of the NMR linewidth
due to the SC diamagnetism and a decrease in the Knight shift are observed,
which are well-understood by the framework of spin-singlet superconductivity.
In contrast, the Knight shift does not change below , and the NMR
spectrum is broadened symmetrically in the SC state in the field range of 3~T
. The unusual NMR spectrum near
suggests that a spatially inhomogeneous SC state such as the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state would be realized.Comment: 5 pages, 5 figure
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