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101.
Seven volcanic rocks from neovolcanic zone of Iceland were analysed for rare-earths (RE). The bulk partition coefficients are estimated from combination of the studied samples. In contrast with the mid-ocean ridge basalts which show the solid-type RE patterns, four of five arbitrarily chosen Icelandic basalts appear to have liquid-type RE patterns. The occurrence of relatively pristine lava with relative unfractionated RE abundances to chondrite is also considered to be associated with the peculiar tectonics of Iceland. 相似文献
102.
A. Schubnel O. Nishizawa K. Masuda X. J. Lei Z. Xue Y. Guégen 《Pure and Applied Geophysics》2003,160(5-6):869-887
— A set of experiments on four samples of Oshima Granite at 15, 40 and 60 MPa confining pressure have been performed in order to investigate the damage behavior of granite submitted to deviatoric stress. In addition an experiment on one sample of Toki Granite at 40 MPa confining pressure was performed, in order to compare and elucidate the structural effects. Using acoustic emission data, strain measurements and elastic wave velocities allow to define consistently a damage domain in the stress space. In this domain, microcracking develops. The microcracking process is, in a first stage, homogeneous and, close to failure, localized. Elastic wave velocities decrease in the damage domain and elastic anisotropy develops. Using Kachanov's model (1993), elastic wave velocities have been inverted to derive the full second-order crack density tensor and characterize the fluid saturation state from the fourth-order crack density tensor. Crack density is strongly anisotropic and the total crack density close to failure slightly above one. The results indicate that the rock is saturated in agreement with the experimental conditions. The model is thus shown to be very appropriate to infer from elastic wave velocities a complete quantitative characterization of the damaged rock. 相似文献
103.
Shingo Yamada Forecast Division Japan Meteorological Agency Tokyo Japan Shuhei Maeda Administration Division Climate Marine Department Japan Meteorological Agency Tokyo Japan K. Gambo c/o Department of Earth Planetary Physi 《大气科学进展》1997,(1)
NotesonExtended-RangeAtmosphericPredictionintheNorthernHemisphereWinterShingoYamadaForecastDivision,JapanMeteorologicalAgency... 相似文献
104.
105.
106.
Atsushi Okamoto Shuhei Tanaka Masaoki Uno Otgonbayar Dandar Kazuki Yoshida 《Island Arc》2024,33(1):e12519
Thermogravimetric (TG) analyses were used to characterize the products and quantify the extent of serpentinization as a stepwise weight loss during heating (TG loss) or its derivative (DTG). Multivariate analyses are powerful tools for extracting information from complicated spectrum data; however, no studies have applied them to characterize serpentinites. In this study, hydrothermal experiments of olivine-H2O, olivine–orthopyroxene-H2O and orthopyroxene-H2O were conducted at 250–400°C and under vapor-saturated pressure. The product minerals observed were serpentine+brucite+magnetite in the olivine-H2O experiments and serpentine±talc in the orthoyroxene-H2O and olivine-orthopyroxene-H2O experiments. These results are consistent with those of previous studies; however, the positions and width of DTG peaks for individual minerals were varied depending on the experimental conditions. To extract systematics from the TG spectra, non-negative matrix factorization (NMF), an unsupervised machine learning technique, was applied to the DTG spectra of the experimental products. NMF revealed that the DTG profiles were explained by a linear combination of six basis spectra, which corresponded to the characteristic products, including three types of serpentine minerals (low-, medium-, and high-T), two types of brucite (low-and high-T), two type of talc (talc+serpentine mixture, well-crystallized talc) with different crystallinity, and noise during the TG measurement. Systematic changes in the factor loading revealed that, in the olivine-H2O systems, the products changed from medium-T serpentine+low-T brucite to high-T serpentine+high-T brucite as serpentinization progressed. In the olivine-orthopyroxene system, low-T serpentine or poorly crystallized talc+serpentine mixture was initially formed, followed by the formation of well-crystallized talc, resulting in dehydration. Applying NMF to DTG showed the mineralogical differences between olivine and orthopyroxene systems and increases of the crystallinity during the progress of serpentinization, suggesting its potential for characterizing various serpentinites within oceanic lithospheres that suffer from several stages of alteration and weathering at different temperatures. 相似文献
107.
INTRODUCTIONDirectionalspectraofwind-generatedwavesareveryimportanttotheresearchrelatedto1.InstituteofPhysicalOceanography,OceanUniversityofQingdao,Qingdao266003,China2.ResearchinstituteforAppliedMechanics,KyUshuUniversity,Kasuga816,Japanwindwaves.Theyfindapplicationinfieldsasdiverseasbasicair-seainteraction,practicalwaveforecasting,satellitesurveillanceandengineeringdesignofmarinestructuresandvehicles.Sincethepioneeringworkofthestereowaveobservationproject(Coteetal.11960),alotofeff… 相似文献
108.
The possible influences of the Emperor Seamounts (ESs) upon the subarctic gyre of the North Pacific (NPSAG) were investigated
by a series of numerical experiments. In the experiments, a two-layer ocean with a meridional mountain ridge was forced by
seasonally varying wind stress. We focused on how the return ratio, the ratio of the boundary transport along the eastern
side of the ridge to the interior Sverdrup transport, changes with ridge height, width and density stratification. It was
found that the return ratio can be large if the ridge width is greater than the width of the viscous boundary layer. In this
case, the bottom pressure torque determines the return ratio; the return ratio is almost proportional to the ridge height
when the ridge height is small and some contours of planetary potential vorticity pass over the ridge. However, the return
ratio is independent of the ridge height and decreases with the stratification when the ridge height is large and all the
contours of planetary potential vorticity are closed. These dependences of the return ratio were understood in terms of barotropic
and baroclinic components of the bottom pressure torque. Implications for the bathymetric influences of ESs on the actual
NPSAG are also discussed. 相似文献
109.
M. Desmet M. Briquet † A. Thoul ‡ W. Zima P. De Cat G. Handler I. Ilyin E. Kambe J. Krzesinski H. Lehmann S. Masuda P. Mathias D. E. Mkrtichian J. Telting K. Uytterhoeven S. L. S. Yang C. Aerts 《Monthly notices of the Royal Astronomical Society》2009,396(3):1460-1472
We present the results of a spectroscopic multisite campaign for the β Cephei star 12 (DD) Lacertae. Our study is based on more than thousand high-resolution high S/N spectra gathered with eight different telescopes in a time span of 11 months. In addition, we make use of numerous archival spectroscopic measurements. We confirm 10 independent frequencies recently discovered from photometry, as well as harmonics and combination frequencies. In particular, the slowly pulsating B-stars (SPB)-like g -mode with frequency 0.3428 d−1 reported before is detected in our spectroscopy. We identify the four main modes as (ℓ1 , m 1 ) = (1, 1), (ℓ2 , m 2 ) = (0, 0), (ℓ3 , m 3 ) = (1, 0) and (ℓ4 , m 4 ) = (2, 1) for f 1 = 5.178 964 d−1 , f 2 = 5.334 224 d−1 , f 3 = 5.066 316 d−1 and f 4 = 5.490 133 d−1 , respectively. Our seismic modelling shows that f 2 is likely the radial first overtone and that the core overshooting parameter αov is lower than 0.4 local pressure scale heights. 相似文献
110.
T. Sako T. Sekiguchi M. Sasaki K. Okajima F. Abe I. A. Bond J. B. Hearnshaw Y. Itow K. Kamiya P. M. Kilmartin K. Masuda Y. Matsubara Y. Muraki N. J. Rattenbury D. J. Sullivan T. Sumi P. Tristram T. Yanagisawa P. C. M. Yock 《Experimental Astronomy》2008,22(1-2):51-66
We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2k×4k pixels, and covers a 2.2 deg2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at ??80° C, at which temperature dark current noise is negligible for a typical 1–3 min exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 s. Readout noise of 2–3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements. 相似文献