72 research outputs found
A 2.75-Approximation Algorithm for the Unconstrained Traveling Tournament Problem
A 2.75-approximation algorithm is proposed for the unconstrained traveling
tournament problem, which is a variant of the traveling tournament problem. For
the unconstrained traveling tournament problem, this is the first proposal of
an approximation algorithm with a constant approximation ratio. In addition,
the proposed algorithm yields a solution that meets both the no-repeater and
mirrored constraints. Computational experiments show that the algorithm
generates solutions of good quality.Comment: 12 pages, 1 figur
Effects of elasticity on wall shear stress in patient-specific aneurysm of cerebral artery
The behavior of wall shear stress (WSS) was previously reported in a deformable aneurysm model using fluid-structure interactions. However, these findings have not been validated. In the present study, we examined the effect of elasticity (i.e. , deformation) on wall shear stress inside a cerebral aneurysm at the apex of a bifurcation using particle image velocimetry in vitro. The flow model simulated a human patient-specific aneurysm at the apex of the bifurcation of the middle cerebral artery. Flow characteristics by wall elasticity were examined for both elastic and non-deformable aneurysm models with pulsatile blood flow. The absolute temporally- and spatially-averaged WSS along the bleb wall was smaller in the elastic model than that in the non-deformable model. This small WSS may be related to attenuation of the WSS. Further, the WSS gradient had a finite value near the stagnation point of the aneurysm dome. Finally, the WSS gradient near the stagnation point was slightly smaller in the elastic model than that in the non-deformable model. These data suggest that elasticity of the aneurysm wall can affect the progression and rupture of aneurysms via hemodynamic stress
Impurity emission characteristics of long pulse discharges in Large Helical Device
Line spectra from intrinsic impurity ions have been monitored during the three kinds of long-pulse discharges (ICH, ECH, NBI). Constant emission from the iron impurity shows no preferential accumulation of iron ion during the long-pulse operations. Stable Doppler ion temperature has been also measured from Fe XX, C V and C III spectra
Design of Metal-to-Metal Charge-Transfer Chromophores for Visible-Light Activation of Oxygen-Evolving Mn Oxide Catalysts in a Polymer Film
To
construct photoresponsive unidirectional charge transfer units
for the activation of oxygen-evolving manganese oxide (MnO<sub><i>x</i></sub>) catalyst, metal-oxide nanoclusters consisting of
cerium (Ce<sup>III</sup>) or cobalt (Co<sup>II</sup>) ions and Keggin-type
polyoxotungstate (PW<sub>12</sub>O<sub>40</sub><sup>3–</sup>) were synthesized in a polymer matrix as visible-light-absorbing
chromophores. The utilization of the polymer matrix enabled the molecularly
dispersed PW<sub>12</sub>O<sub>40</sub><sup>3–</sup> states
and was advantageous to achieve product-separable energy conversion
systems. The reaction of PW<sub>12</sub>O<sub>40</sub><sup>3–</sup> with Ce(NO<sub>3</sub>)<sub>3</sub> or CoCl<sub>2</sub> in the polymer
matrix generated the new broad absorption tails extending from the
UV to visible region, assignable to metal-to-metal charge transfer
(MMCT) transitions of oxo-bridged binuclear W<sup>VI</sup>–O–Ce<sup>III</sup> and W<sup>VI</sup>–O–Co<sup>II</sup> units.
Cyclic voltammetry analysis of the oxo-bridged binuclear units in
the polymer membrane revealed that the Co<sup>III</sup>/Co<sup>II</sup> couple had a 300 mV more positive redox potential than that of Ce<sup>IV</sup>/Ce<sup>III</sup> and was capable of extracting electrons
from MnO<sub><i>x</i></sub> catalyst. Although visible-light
irradiation of the polymer membrane having W<sup>VI</sup>–O–Co<sup>II</sup> units resulted in negligible photocurrent generation, a
clear anodic photocurrent response assigned to photoinduced W<sup>VI</sup>–O–Co<sup>II</sup> → W<sup>V</sup>–O–Co<sup>III</sup> transition was observed after the coupling of MnO<sub><i>x</i></sub> catalysts to W<sup>VI</sup>–O–Co<sup>II</sup> units. This finding demonstrated that the generation of
anodic photocurrent is derived from the activation of MnO<sub><i>x</i></sub> catalyst by the photogenerated Co<sup>III</sup> through
confined W<sup>VI</sup>–O–Co<sup>II</sup> linkages.
The system in this work based on POM and polymer, and its synthetic
method provide us a novel methodology to develop artificial photosynthetic
systems with spatially and energetically optimized components
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