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- Adam, A, et al.
(författare)
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Abstracts from Hydrocephalus 2016.
- 2017
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Ingår i: Fluids and Barriers of the CNS. - : Springer Science and Business Media LLC. - 2045-8118. ; 14:Suppl 1
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Tidskriftsartikel (refereegranskat)
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- Kawaguchi, K., et al.
(författare)
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Detection of HF Toward PKS 1830-211, Search for Interstellar H2F+, and Laboratory Study of H2F+ and H2Cl+ Dissociative Recombination
- 2016
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 822:2, s. Art. no. 115-
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Tidskriftsartikel (refereegranskat)abstract
- We report extragalactic observations of two fluorine-bearing species, hydrogen fluoride (HF) and fluoronium (H2F+), in the z = 0.89 absorber in front of the lensed blazar PKS 1830-211 with the Atacama Large Millimeter/submillimeter Array. HF was detected toward both southwest and northeast images of the blazar, with column densities >3.4 × 1014 cm-2 and 0.18 × 1014 cm-2, respectively. H2F+ was not detected, down to an upper limit (3?) of 8.8 × 1011 cm-2 and an abundance ratio of [H2F+]/[HF] 1/386. We also searched for H2F+ toward the Galactic sources NGC 6334 I and W51C, and toward Galactic center clouds with the Herschel HIFI spectrometer.6 The upper limit on the column density was derived to be 2.5 × 1011 cm-2 in NGC 6334 I, which is 1/68 of that for H2Cl+. In constrast, the ortho transition of H2Cl+ is detected toward PKS 1830-211. To understand the small abundance of interstellar H2F+, we carried out laboratory experiments to determine the rate constants for the ion-electron recombination reaction by infrared time-resolved spectroscopy. The constants determined are ke(209 K) = (1.1 ± 0.3) ×10-7 cm3 s-1 and (0.46 ± 0.05) ×10-7 cm3 s-1 for H2F+ and H2Cl+, respectively. The difference in the dissociative recombination rates between H2F+ and H2Cl+ by a factor ?2 and the cosmic abundance ratio [F]/[Cl] ? 1/6 are not enough to explain the much smaller abundance of H2F+. The difference in the formation mechanism of H2F+ and H2Cl+ in interstellar space would be a major factor in the small abundance of H2F+.
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- Aihara, Aya, et al.
(författare)
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A Vibration Estimation Method for Wind Turbine Blades
- 2017
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Ingår i: Experimental mechanics. - : Springer Science and Business Media LLC. - 0014-4851 .- 1741-2765. ; 57:8, s. 1213-1224
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the development of a vibration monitoring system for wind turbine blades. This system is used to estimate the deflection at the tip blade on a wind turbine tower. Technical accidents of wind turbine blades have become increasingly common. Thus, regular monitoring of the blades is very important to prevent breakdowns, especially in cases when the blades begin to vibrate excessively. The monitoring system developed in this study satisfies two main objectives for practicality. First, our system is easy to install on existing wind turbines. Second, blade deflection is measured in real time. Our system can be operated using a few strain gages attached at the blade root, and the deflection is calculated based on the monitored stress. Thus, direct measurement of deflection at the blade tip is unnecessary. An estimation algorithm for this purpose is adopted based on the experimental modal analysis. This paper focuses on the evaluation of the estimation algorithm to investigate the feasibility of our system. Basic experiments were conducted using a simple blade model of a 300 W scaled wind turbine under rotation. Signals from the strain gages were acquired by a sensor network and sent to a computer through a wireless connection. The results show that the estimation accuracy is acceptably high. Therefore, we conclude that our proposed system is practical.
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- Muller, Sebastien, 1976, et al.
(författare)
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Detection of extragalactic CF+ toward PKS 1830-211 Chemical differentiation in the absorbing gas
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 589, s. Art. no. L5-
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Tidskriftsartikel (refereegranskat)abstract
- We report the first extragalactic detection of the fluoromethylidynium ion CF+ in the z = 0.89 absorber toward PKS 1830-211. We estimate an abundance of similar to 3 x 10(-10) relative to H-2 and that similar to 1% of fluorine is captured in CF+. The absorption line profile of CF+ is found to be markedly different from that of other species observed within the same tuning, and is notably anticorrelated with CH3OH. On the other hand, the CF+ profile resembles that of [CI]. Our results are consistent with expected fluorine chemistry and point to chemical differentiation in the column of absorbing gas.
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