...potential between-leg deficits in horizontal force may not be considered during testing due to the bilateral nature of sprinting. ...this study aimed to establish the reliability of unilateral ...tests assessing explosive hip extension and horizontal force production, and their association with sprinting performance. Reliability was established by calculating typical error (TE), coefficient of variation (TE%), interclass correlation coefficient (ICC) and minimal detectable change (MDC). Results Test re-test reliability was good to excellent for the scooter (TE%= 1.7-4.6; ICC= 0.88-0.94), moderate for the isometric hip extension (TE%= 5.6-6.0; ICC = 0.65-0.69) and good for the hamstring switch (TE%= 3.4-4.7; ICC = 0.78 to 0.87) and single hop for distance (TE%= 4.7-5.7; ICC= 0.78-0.86).
The current elasticities of major mantle transition zone minerals and their hydrous counterparts, such as wadsleyite, ringwoodite, and majorite garnet, have the velocity gradients several times lower ...than those of the Earth models. Here we use ultrasonic interferometry technique to measure the sound velocities of wadsleyite (Mg0.91Fe0.09)2SiO4 at pressures up to 14 GPa and room temperature. Compared with previous studies, we have obtained possibly the highest ∂VP/P and ∂KS/P value at transition zone pressure, which are still noticeably lower than the Earth models, such as the preliminary reference Earth model, ak135, iasp91, etc. The results indicate that the VP contrast of “dry” olivine‐wadsleyite transition at 410 km is higher than previous thought, while that of wadsleyite‐ringwoodite transition at 520 km is noticeably low. Using the current and previous data on “dry” and hydrous wadsleyite a water “gradient” model at upper mantle transition zone were proposed and discussed.
Plain Language Summary
Olivine and its high pressure polymorphs (wadsleyite and ringwoodite) are the major components in the Earth's upper mantle and mantle transition zone, which dominant the physical properties of the Earth's mantle. However, using the current pyrolitic model and the measured elasticities (velocities and moduli) of wadsleyite and ringwoodite, one cannot reproduce the observed velocity profiles of the Earth models (e.g., preliminary reference Earth model, ak135). Ultrasonic interferometry technique is a mature technique to measure the compressional and shear wave velocities of polycrystalline aggregates. Using this technique, we obtained the sound velocities and their pressure (depth) dependences of iron‐bearing wadsleyite at pressures up to 14 GPa and room temperature. The results suggest that under dry condition, the seismic velocity contrasts at 410 km discontinuity (olivine‐wadsleyite transition) are higher than previous reported. To match the velocity contrasts at 410 km depth and the high velocity gradients at mantle transition zone, a hydrous transition zone with water “gradient” is proposed based on this study and previous results.
Key Points
Sound velocities of (Mg0.91Fe0.09)2SiO4 Wadsleyite were measured up to 14 GPa at room temperature
Possibly the highest ∂VP/P and KS′ values were obtained, which are still much lower than those of the Earth models
Water content “gradient” was proposed to match the high velocity gradients in the mantle transition zone
For the seismic source generated by the high-speed rail with viaduct, a theoretical method is proposed to measure the apparent velocity of the high-speed rail wavefield generated by a moving source ...set by using crosscorrelation of the waves recorded by multiple stations. Furthermore, synthetic data of the high-speed rail wavefields in layered media is generated, and the apparent velocity of a phase in it is calculated. The correctness of the method is verified compared with the theoretical results.
The Radial Velocity of OGLE-2015-BLG-0966S Johnson, Samson A; Yee, Jennifer C
Publications of the Astronomical Society of the Pacific,
07/2017, Letnik:
129, Številka:
977
Journal Article
Recenzirano
The distance to the planetary system OGLE-2015-BLG-0966L and the separation between the planet and its host star are ambiguous due to an ambiguity in the distance to the source star. We attempt to ...break this degeneracy by measuring the systemic radial velocity of the source star measured from a spectrum taken while the source was highly magnified. Our measurement of vLSR =54.2 ± 0.3 km s-1 does not definitively resolve the nature of the source, but supports the general conclusion that the source is in the bulge. This work demonstrates that even a low signal-to-noise spectrum has the potential to provide useful information for characterizing microlensing source stars.
(Ti,Mo)(C,N)-25 wt% Ni coatings obtained by spraying an agglomerated and sintered feedstock powder using different high velocity air-fuel (HVAF) and high velocity oxygen-fuel (HVOF) deposition ...processes are comparatively analysed for their sliding, abrasion and impact resistance.
All HVOF-sprayed coatings are particularly dense, with ≈800 HV hardness (tested at 100 gf, 300 gf and 500 gf). In-flight oxidation resulted in some embrittlement, as revealed by scratch tests. In ball-on-disk sliding against an Al2O3 counterpart, they maintained a mild wear regime (wear rates ≤10−6 mm3/(N⋅m)) from room temperature up to 600 °C, with better performance in comparison to Cr3C2–NiCr reference coatings. At room temperature, the Ti(C,N) hard phase limited the abrasive cutting by counterbody asperities. At 400 °C and 600 °C, the coatings developed a thin, protective oxide tribofilm. They also exhibited no interface delamination in cyclic impact tests. However, they suffered higher wear (≈3–5 × 10−3 mm3/(N⋅m)) in high-stress particle abrasion testing, particularly when compared to HVAF-sprayed Cr3C2–NiCr. Gaining improved control over in-flight oxidation of (Ti,Mo)(C,N)–Ni during spraying is probably the key to overcome this limitation.
The HVAF-sprayed (Ti,Mo)(C,N)–Ni coating exhibited severe interlamellar decohesion under all test conditions, as the limited melting degree of the feedstock did not compensate for the intrinsic microstructural inhomogeneity of the powder particles.
•HVOF (Ti,Mo)(C,N)–Ni exhibited better sliding wear resistance than Cr3C2–NiCr up to 600 °C.•HVOF (Ti,Mo)(C,N)–Ni is not sensitive to the p × V factor over a tested range of 1–25 MPa × m/s.•Oxide inclusion and ensuing brittleness worsened the resistance of HVOF coatings to high-stress particles' abrasion.•The coatings did not delaminate under cyclic impact conditions.•The HVAF coating is less homogeneous and weaker because the Ni matrix did not melt under the chosen deposition conditions.
Aiming at the problem that lack of the measured sound velocity profile (SVP) leads to the unreliable underwater positioning solution, this paper proposed an efficient underwater positioning method by ...the self-constraint conditions of water depth and sound velocity gradient. To construct the depth constraint condition, the sound propagation distance error model is deduced by acoustic ray tracing, and the sound vertical propagation error model related to the incident angle and sound velocity error is given firstly. By fitting the vertical propagation error model, the reference depth is solved, and the vertical propagation distances between the transducer and the underwater control points of all observation epochs are gotten. Then with the solved vertical distance of each epoch and the sound velocity gradient from neighbor SVPs as the constraint conditions, the SVP is retrieved by the simulated annealing (SA) algorithm. With the retrieved SVP, the underwater positioning can be performed when the measured SVP is absent. The proposed method was verified by an experiment in the 3000 m depth water area of the South China Sea. The results achieved 2.07 m/s of standard deviation of the SVP inversion, centimeter-level horizontal positioning accuracy and 0.54 m of vertical positioning accuracy under the circumstance of lack of SVP measurement.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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