3,827 research outputs found
The Light and Period Variations of the Eclipsing Binary BX Draconis
New CCD photometric observations of BX Dra were obtained for 26 nights from
2009 April to 2010 June. The long-term photometric behaviors of the system are
presented from detailed studies of the period and light variations, based on
the historical data and our new observations. All available light curves
display total eclipses at secondary minima and inverse O'Connell effects with
Max I fainter than Max II, which are satisfactorily modeled by adding the
slightly time-varying hot spot on the primary star. A total of 87 times of
minimum light spanning over about 74 yrs, including our 22 timing measurements,
were used for ephemeris computations. Detailed analysis of the O-C diagram
showed that the orbital period has changed in combinations with an upward
parabola and a sinusoidal variation. The continuous period increase with a rate
of +5.65 \times 10^-7 d yr^-1 is consistent with that calculated from the
Wilson-Devinney synthesis code. It can be interpreted as a mass transfer from
the secondary to the primary star at a rate of 2.74 \times 10^-7 M\odot yr^-1,
which is one of the largest rates for contact systems. The most likely
explanation of the sinusoidal variation with a period of 30.2 yrs and a
semi-amplitude of 0.0062 d is a light-traveltime effect due to the existence of
a circumbinary object. We suggest that BX Dra is probably a triple system,
consisting of a primary star with a spectral type of F0, its secondary
component of spectral type F1-2, and an unseen circumbinary object with a
minimum mass of M3 = 0.23 M\odot.Comment: 24 pages, including 5 figures and 9 tables, accepted for publication
in PAS
Electrical Investigation of the Oblique Hanle Effect in Ferromagnet/Oxide/Semiconductor Contacts
We have investigated the electrical Hanle effect with magnetic fields applied
at an oblique angle ({\theta}) to the spin direction (the oblique Hanle effect,
OHE) in CoFe/MgO/semiconductor (SC) contacts by employing a three-terminal
measurement scheme. The electrical oblique Hanle signals obtained in
CoFe/MgO/Si and CoFe/MgO/Ge contacts show clearly different line shapes
depending on the spin lifetime of the host SC. Notably, at moderate magnetic
fields, the asymptotic values of the oblique Hanle signals (in both contacts)
are consistently reduced by a factor of cos^2({\theta}) irrespective of the
bias current and temperature. These results are in good agreement with
predictions of the spin precession and relaxation model for the electrical
oblique Hanle effect. At high magnetic fields where the magnetization of CoFe
is significantly tilted from the film plane to the magnetic field direction, we
find that the observed angular dependence of voltage signals in the CoFe/MgO/Si
and CoFe/MgO/Ge contacts are well explained by the OHE, considering the
misalignment angle between the external magnetic field and the magnetization of
CoFe.Comment: 19 pages, 8 figure
Flow-Induced Voltage Generation Over Monolayer Graphene in the Presence of Herringbone Grooves
While flow-induced voltage over a graphene layer has been reported, its origin remains unclear. In our previous study, we suggested different mechanisms for different experimental configurations: phonon dragging effect for the parallel alignment and an enhanced out-of-plane phonon mode for the perpendicular alignment (Appl. Phys. Lett. 102:063116, 2011). In order to further examine the origin of flow-induced voltage, we introduced a transverse flow component by integrating staggered herringbone grooves in the microchannel. We found that the flow-induced voltage decreased significantly in the presence of herringbone grooves in both parallel and perpendicular alignments. These results support our previous interpretation
Clock Light Design Based on Sunrise and Sunset Time
We intend to develop a clock with a natural human perception of time,
instead of a numerical one. Our representation of time was inspired by the
difference in light during sunrise and sunset depending on the season or place
and its annual recurrence. The events of sunrise, midday, and sunset, which
consist our time series, was appointed a specific color based on the theory
associated with color temperature, and connected with gradation. To be able
to show the time information with light, we created a physical form. This
clock light functions as an indirect light source and gives emotional value to
time
Perception-Oriented Single Image Super-Resolution using Optimal Objective Estimation
Single-image super-resolution (SISR) networks trained with perceptual and
adversarial losses provide high-contrast outputs compared to those of networks
trained with distortion-oriented losses, such as L1 or L2. However, it has been
shown that using a single perceptual loss is insufficient for accurately
restoring locally varying diverse shapes in images, often generating
undesirable artifacts or unnatural details. For this reason, combinations of
various losses, such as perceptual, adversarial, and distortion losses, have
been attempted, yet it remains challenging to find optimal combinations. Hence,
in this paper, we propose a new SISR framework that applies optimal objectives
for each region to generate plausible results in overall areas of
high-resolution outputs. Specifically, the framework comprises two models: a
predictive model that infers an optimal objective map for a given
low-resolution (LR) input and a generative model that applies a target
objective map to produce the corresponding SR output. The generative model is
trained over our proposed objective trajectory representing a set of essential
objectives, which enables the single network to learn various SR results
corresponding to combined losses on the trajectory. The predictive model is
trained using pairs of LR images and corresponding optimal objective maps
searched from the objective trajectory. Experimental results on five benchmarks
show that the proposed method outperforms state-of-the-art perception-driven SR
methods in LPIPS, DISTS, PSNR, and SSIM metrics. The visual results also
demonstrate the superiority of our method in perception-oriented
reconstruction. The code and models are available at
https://github.com/seungho-snu/SROOE.Comment: Code and trained models will be available at
https://github.com/seungho-snu/SROO
Batalin-Tyutin Quantization of the Chiral Schwinger Model
We quantize the chiral Schwinger Model by using the Batalin-Tyutin formalism.
We show that one can systematically construct the first class constraints and
the desired involutive Hamiltonian, which naturally generates all secondary
constraints. For , this Hamiltonian gives the gauge invariant Lagrangian
including the well-known Wess-Zumino terms, while for the corresponding
Lagrangian has the additional new type of the Wess-Zumino terms, which are
irrelevant to the gauge symmetry.Comment: 15 pages, latex, no figures, to be published in Z. Phys. C (1995
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