1,141 research outputs found
Black-Hole X-Ray Transients: The Effect of Irradiation on Time-Dependent Accretion Disk Structure
Some effects of irradiation on time-dependent accretion-disk models for black
hole X-ray novae are presented. Two types of irradiation are considered: direct
irradiation from the inner hot disk and indirect irradiation as might be
reflected by a corona or chromosphere above the disk. The shadowing effect of
the time-dependent evolution of the disk height and consequent blocking of the
outer disk by the inner and middle portions of the disk from the direct
irradiation is included. The direct irradiation of the disk by inner layers
where the soft X-ray flux is generated is found to have only a small effect on
the outer disk because of shadowing. Mild indirect irradiation that flattens,
but otherwise does not affect the light curve substantially, still has
interesting non-linear effects on the structure of the disk as heating and
cooling waves propagate. The irradiated disks do not always make simple
transitions between the hot and cold states, but can linger at intermediate
temperatures or even return temporarily to the hot state, depending on the
irradiation and the activity in adjacent portions of the disk.Comment: 12 pages, 8 figure
Improving Kinematic Accuracy of Soft Wearable Data Gloves by Optimizing Sensor Locations
Bending sensors enable compact, wearable designs when used for measuring hand configurations in data gloves. While existing data gloves can accurately measure angular displacement of the finger and distal thumb joints, accurate measurement of thumb carpometacarpal (CMC) joint movements remains challenging due to crosstalk between the multi-sensor outputs required to measure the degrees of freedom (DOF). To properly measure CMC-joint configurations, sensor locations that minimize sensor crosstalk must be identified. This paper presents a novel approach to identifying optimal sensor locations. Three-dimensional hand surface data from ten subjects was collected in multiple thumb postures with varied CMC-joint flexion and abduction angles. For each posture, scanned CMC-joint contours were used to estimate CMC-joint flexion and abduction angles by varying the positions and orientations of two bending sensors. Optimal sensor locations were estimated by the least squares method, which minimized the difference between the true CMC-joint angles and the joint angle estimates. Finally, the resultant optimal sensor locations were experimentally validated. Placing sensors at the optimal locations, CMC-joint angle measurement accuracies improved (flexion, 2.8° ± 1.9°; abduction, 1.9° ± 1.2°). The proposed method for improving the accuracy of the sensing system can be extended to other types of soft wearable measurement devices
Robustness of multiparty nonlocality to local decoherence
We investigate the robustness of multiparty nonlocality under local
decoherence, acting independently and equally on each subsystems. To be
specific, we consider an N-qubit GHZ state under depolarization, dephasing, or
dissipation channel, and tested the nonlocality by violation of Mermin-Klyshko
inequality, which is one of Bell's inequalities for multi-qubit systems. The
results show that the robustness of nonlocality increases with the number of
qubits, and that the nonlocality of an N-qubit GHZ state with even N is
extremely persistent against dephasing.Comment: 5 pages, 4 figure
Current-induced domain wall motion in a nanowire with perpendicular magnetic anisotropy
We study theoretically the current-induced magnetic domain wall motion in a
metallic nanowire with perpendicular magnetic anisotropy. The anisotropy can
reduce the critical current density of the domain wall motion. We explain the
reduction mechanism and identify the maximal reduction conditions. This result
facilitates both fundamental studies and device applications of the current-
induced domain wall motion
Monitoring of multi-frequency polarization of gamma-ray bright AGNs
We started two observing programs with the Korean VLBI Network (KVN)
monitoring changes in the flux density and polarization of relativistic jets in
gamma-ray bright AGNs simultaneously at 22, 43, 86, 129 GHz. One is a
single-dish weekly-observing program in dual polarization with KVN 21-m
diameter radio telescopes beginning in 2011 May. The other is a VLBI
monthly-observing program with the three-element VLBI network at an angular
resolution range of 1.0--9.2 mas beginning in 2012 December. The monitoring
observations aim to study correlation of variability in gamma-ray with that in
radio flux density and polarization of relativistic jets when they flare up.
These observations enable us to study the origin of the gamma-ray flares of
AGNs.Comment: 4 pages, 4 figures, Proceedings of the conference "The innermost
regions of relativistic jets and their magnetic fields", Granada, Spai
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