204 research outputs found
Super-Eddington Black-Hole Models for SS 433
We examine highly super-Eddington black-hole models for SS 433, based on
two-dimensional hydrodynamical calculations coupled with radiation transport.
The super-Eddington accretion flow with a small viscosity parameter,
, results in a geometrically and optically thick disk with
a large opening angle of to the equatorial plane and a very
rarefied, hot, and optically thin high-velocity jets region around the disk.
The thick accretion flow consists of two different zones: an inner
advection-dominated zone and an outer convection-dominated zone. The
high-velocity region around the disk is divided into two characteristic
regions, a very rarefied funnel region along the rotational axis and a
moderately rarefied high-velocity region outside of the disk. The temperatures
of K and the densities of g cm in the upper
disk vary sharply to K and g cm, respectively,
across the disk boundary between the disk and the high-velocity region. The
X-ray emission of iron lines would be generated only in a confined region
between the funnel wall and the photospheric disk boundary, where flows are
accelerated to relativistic velocities of 0.2 due to the dominant
radiation-pressure force. The results are discussed regarding the collimation
angle of the jets, the large mass-outflow rate obserevd in SS 433, and the
ADAFs and the CDAFs models.Comment: 19 pages, 11 figures, to be published in Publ. Astron. Soc. Japan,
200
Evolution of MHD Torus and Mass Outflow Around Spinning AGN
We perform axisymmetric, two-dimensional magnetohydrodynamic (MHD)
simulations to investigate accretion flows around spinning AGN. To mimic the
space-time geometry of spinning black holes, we consider effective Kerr
potential, and the mass of the black holes is . We initialize
the accretion disc with a magnetized torus by adopting the toroidal component
of the magnetic vector potential. The initial magnetic field strength is set by
using the plasma beta parameter (). We observe self-consistent
turbulence generated by magneto rotational instability (MRI) in the disc. The
MRI turbulence transports angular momentum in the disc, resulting in an angular
momentum distribution that approaches a Keplerian distribution. We investigate
the effect of the magnetic field on the dynamics of the torus and associated
mass outflow from the disc around a maximally spinning black hole . For the purpose of our analysis, we investigate the magnetic state of
our simulation model. The model indicates the behaviour similar
to the "magnetically arrested disk (MAD)'' state, and all the other low
magnetic model remains in the SANE state. We observe that mass outflow rates
are significantly enhanced with the increased magnetic field in the disc. We
find a positive correlation between the magnetic field and mass outflow rates.
We also investigate the effect of black hole spin on the magnetized torus
evolution. However, we have not found any significant effect of black hole spin
on mass outflows in our model. Finally, we discuss the possible astrophysical
applications of our simulation results.Comment: 15 pages, 13 figures (2 appendix figures), Accepted for publication
in MNRA
Time delays between radio and X-ray and between narrow radio bands of Sgr A* flares in the shock oscillation model
We examine the time delay between radio and X-ray and between narrow radio
frequency flares in Sagittarius A* (Sgr A*), from analyses of the synchrotron,
bremsstrahlung and monochromatic luminosity curves. Using the results of 2D
relativistic radiation magnetohydrodynamic (MHD) simulations based on the shock
oscillation model, we find three types of time delay between the synchrotron
and bremsstrahlung emissions: Type A with a time delay of 2 -- 3 h on the shock
descending branch, Type B with no time delay and Type C with an inverse time
delay of 0.5 -- 1 h on the shock ascending branch. The time delays in Types A
and C are interpreted as a transit time of Alfv\'{e}n and acoustic waves
between both emission dominant regions, respectively. The delay times between
22 and 43 GHz flares and between 8 and 10 GHz flares are 13 -- 26 min
and 13 min, respectively, while the inverse delay also occurs dependently on
the shock location branch. These time delays between the narrow radio bands are
interpreted as the transit time of the acoustic wave between the
frequency-dependent effective radii , at which the
optical depth at the accretion disc surface becomes
unity. The shock oscillation model explains well the observed delay times of
0.5 -- 5 h between radio and X-ray, 20 -- 30 min between 22 and 43 GHz and
18 min between 8 and 10 GHz in Sgr A*.Comment: 14 pages, 14 figures, (accepted for publication in MNRAS
Progress of Photodynamic Therapy in Gastric Cancer
Progress of photodynamic therapy (PDT) in gastric cancer and the clinical outcome are
described in this paper. (1) We included the whole lesion and a 5 mm margin in the field for
irradiation. Marking by injection of India-ink showing the irradiation field was performed
beforehand. (2) We established the standard light dose to be 90 J/cm2 for an argon dye
laser and 60 J/cm2 for a pulse wave laser. (3) The size of cancerous lesion curable by PDT
was expanded from 3 cm in diameter, i.e. 7 cm2 in area to 4 cm in diameter, i.e. 13 cm2 by
employing a new excimer dye laser model, which could emit 4mJ/pulse with 80 Hz pulse
frequency. (4) The depth of cancer invasion which could be treated by PDT was increased from
about 4 mm, i.e. the superficial part of the submucosal layer (SM-1) to more than 10 mm in
depth, i.e. the proper muscular layer. These improvements owe much to the pulse laser, the
photodynamic action induced by which permits deeper penetration than that of a continuous
wave laser. (5) We employed a side-viewing fiberscope for gastric PDT to irradiate the lesion
from an angle of 90°. (6) We designed a simple cut quartz fiber for photoradiation with a spiral spring thickened toward the end. (7) We developed an endoscopic device for photoradiation in
PDT which achieves accurate and efficient irradiation. As a result of these improvements a
higher cure rate was obtained even with a lower light dose of irradiation
Direct mapping of the spin-filtered surface bands of a three-dimensional quantum spin Hall insulator
Spin-polarized band structure of the three-dimensional quantum spin Hall
insulator (x=0.12-0.13) was fully elucidated by
spin-polarized angle-resolved photoemission spectroscopy using a high-yield
spin polarimeter equipped with a high-resolution electron spectrometer. Between
the two time-reversal-invariant points, and , of the
(111) surface Brillouin zone, a spin-up band ( band) was found to
cross the Fermi energy only once, providing unambiguous evidence for the strong
topological insulator phase. The observed spin-polarized band dispersions
determine the "mirror chirality" to be -1, which agrees with the theoretical
prediction based on first-principles calculations
ネットワークカメラによる侵入物検出システムの運用における問題の検討
危険区域や重要施設の侵入監視や不審物の検出を行うシステムは,犯罪や事故を未然に防止するためには重要なものである. 画像処理により侵入者を検出処理するシステムの一つとして,我々は複数枚の静止画像を用いるイメージベースドレンダリングを応用した侵入物検出手法システムを提案している.本稿では,イメージベースドレンダリングを応用した侵入物検出処理を行うシステムを複数台のネットワークカメラを用いて構築・運用する際の問題として,カメラ画像の転送用に確保すべきネットワーク帯域,カメラと計算機間の距離を考慮したシステムの処理時間について検討する
照明条件に依存しない手法に基づいた侵入物検出システムのネットワークカメラによる構築
特別企画「学生ポスターセッション
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