Multi-Wavelength Observation of the 3n/x3.3 Flare of 28 November 1998     

You  Jianqi  Li  Hui  Fan  Zhongyu  Sakurai  Takashi 《Solar physics》2001,203(1):107-117

The 3N/X3.3 flare of 28 November 1998 was observed in multiple wavelength simultaneously. The available data include H images, spectra in Hei 1083 nm and Caii 854.2 nm from Purple Mountain Observatory (PMO), soft X-ray (SXR) and hard X-ray (HXR) images and flux from Yohkoh. Morphological relationship investigation and spectral analysis of these data show: (1) The sudden brightening at loop top above the active region and the steep increase of SXR flux before flare onset suggest that the corona there had already been heated to some extent in the preflare phase. (2) The scales of the Caii 854.2 nm emission areas are very similar to those of the H line, but the emission profiles look like those of the Caii K line. Most of the Hei 1083 nm emissions exist in the bright H kernels and can last to the decay phase. (3) Flare spectra show that line shift and asymmetry are very common in this flare not only in the impulsive phase but also in the decay phase. The difference in the line shifts or asymmetry between Caii 854.2 nm and Hei 1083 nm, as well as the difference between the line center and wings of Caii 854.2 nm imply the existence of a velocity gradient in the line-of-sight direction. (4) Post-flare loops with very deep absorption (70%) and very-high-velocity red shifts (30–90 km s^–1) were observed in Hei 1083 nm during the decay phase. However, only a slight dip can be found in the Caii 854.2 nm profile.  相似文献   

Rare Earth Elements in Hydrothermally Altered Granitic Rocks in the Ranong and Takua Pa Tin‐Field,Southern Thailand     

Akira Imai  Kotaro Yonezu  Kenzo Sanematsu  Takashi Ikuno  Shingo Ishida  Koichiro Watanabe  Visut Pisutha‐Arnond  Somchai Nakapadungrat  Jarupong Boosayasak 《Resource Geology》2013,63(1):84-98

Geochemical studies were conducted on the hydrothermally altered granitic rocks in the Ranong and Takua Pa tin‐fields in southern Thailand in order to investigate the mode of occurrence of REE (rare earth elements), with emphasis placed on a potential REE resource associated with granitic rocks in the Southeast Asian Tin Belt. The total REE (ΣREE) content of altered granitic rocks ranges from 130 to 350 ppm at Haad Son Paen (which is presently mined for kaolin clay) in the Ranong tin‐field, and that of altered granitic rocks and kaolinite veinlets reaches up to 424 ppm and 872 ppm, respectively, at Nok Hook in the Takua Pa tin‐field. Rare earth elements in the altered granitic rocks and kaolinite veinlets show a relatively flat chondrite‐normalized pattern, thus enriched in heavy REE compared with the original granitic rocks and their weathered crusts. At Nok Hook (Takua Pa), the ΣREE content of kaolinite separated from an altered granitic rock by elutriation is 1313 ppm, a ΣREE amount about four times higher than that of whole‐rock composition of the altered granitic rock. Chondrite‐normalized REE patterns of the elutriated kaolinite and of the altered granite are relatively flat. Sequential extraction experiments suggest that 41 and 85 percent of REE are present as ion exchangeable‐form in the altered granitic rock, and in the kaolinite veinlets, respectively. In addition, more than 90% of REE in the kaolinite veinlets are present as the acid‐soluble state. On the other hand, the ΣREE content of kaolinite veinlets and of the kaolinite concentrated by elutriation from an altered granitic rock at Haad Som Paen (Ranong) is 70 ppm and 75 ppm, respectively, thus enrichment of REE in kaolinite was not confirmed. In addition, by the sequential extraction experiments, 23% and 4% of REE were extracted from the altered granitic rock and the kaolinite veinlets at Haad Som Paen. In the altered granitic rocks at Haad Som Paen, REE are present as refractory phases, and REE in the acid‐soluble states had been leached by hydrothermal fluid.  相似文献   

Comparison of the lethal effect of CO2 and acidification on red sea bream (Pagrus major) during the early developmental stages     

Kikkawa T  Kita J  Ishimatsu A 《Marine pollution bulletin》2004,48(1-2):108-110

To compare the acute toxicity of CO(2)- and HCl-acidified seawater, eggs and larvae of a marine fish, Pagrus major, were exposed to seawater equilibrated with CO(2)-enriched gas mixtures (CO(2)=5% or 10%, O(2)=20.95% balanced with N(2)) or seawater acidified with 1 N HCl at two pH levels (pH 6.2 (=5% CO(2)) and 5.9 (=10% CO(2))) for 6 h (eggs) or 24 h (larvae). Mortalities of eggs were 85.8% (CO(2)) and 3.6% (HCl) at pH 6.2, and 97.4% (CO(2)) and 0.9% (HCl) at pH 5.9, while those of larvae were 61.2% (CO(2)) and 1.6% (HCl) at pH 6.2, and 100% (CO(2)) and 5.0% (HCl) at pH 5.9. Thus, previous research on the effects of acidified seawater on marine organisms, as a substitute for CO(2), has largely underestimated the toxic effects of CO(2).  相似文献   

Decision-theoretic sensitivity analysis for reservoir development under uncertainty using multilevel quasi-Monte Carlo methods     

Takashi Goda  Daisuke Murakami  Kei Tanaka  Kozo Sato 《Computational Geosciences》2018,22(4):1009-1020

At various stages of petroleum reservoir development, we encounter a large degree of geological uncertainty under which a rational decision has to be made. In order to identify which parameter or group of parameters significantly affects the output of a decision model, we investigate decision-theoretic sensitivity analysis and its computational issues in this paper. In particular, we employ the so-called expected value of partial perfect information (EVPPI) as a sensitivity index and apply multilevel Monte Carlo (MLMC) methods to efficient estimation of EVPPI. In a recent paper by Giles and Goda, an antithetic MLMC estimator for EVPPI is proposed and its variance analysis is conducted under some assumptions on a decision model. In this paper, for an improvement on the performance of the MLMC estimator, we incorporate randomized quasi-Monte Carlo methods within the inner sampling, which results in an multilevel quasi-Monte Carlo (MLQMC) estimator. We apply both the antithetic MLMC and MLQMC estimators to a simple waterflooding decision problem under uncertainty on absolute permeability and relative permeability curves. Through numerical experiments, we compare the performances of the MLMC and MLQMC estimators and confirm a significant advantage of the MLQMC estimator.  相似文献   

Petrology and shock history of the first depleted-like poikilitic shergottite Asuka 12325     

Atsushi Takenouchi  Akira Yamaguchi  Takashi Mikouchi  Richard Greenwood  Sojiro Yamazaki 《Meteoritics & planetary science》2023,58(10):1406-1428

Asuka (A) 12325 is the first poikilitic shergottite having a depleted pattern in light rare earth elements (REE). Compared with known poikilitic shergottites, A 12325 has smaller but more abundant pyroxene oikocrysts with remarkable Fe-rich pigeonite rims, indicating that A 12325 cooled relatively faster at a shallower part of the crust. The redox condition (logfO₂ = IW + 0.6-IW + 1.7) and Fe-rich chemical compositions of each mineral in A 12325 are close to enriched shergottites. The intermediate shergottites could not form by a simple mixing between parent magmas of A 12325 and enriched shergottites. Although A 12325 contains various high-pressure minerals such as majorite and ringwoodite, plagioclase is only partly maskelynitized. Therefore, the maximum shock pressure may be within 17–22 GPa. Thermal conduction and ringwoodite growth calculation around a shock vein revealed that the shock dwell time of A 12325 is at least 40 ms. The weaker shock pressure and longer shock dwell time in A 12325 may be attained by an impact event similar to those of nakhlites and Northwest Africa (NWA) 8159. Such a weak shock ejection event may be as common on Mars as a severe shock event recorded in shergottites. Alteration of sulfide observed in A 12325 may imply the presence of magmatic fluid in its reservoir on Mars. A 12325 expands a chemical variety of Martian rocks and has a unique shock history among poikilitic shergottites while A 12325 also implies that poikilitic shergottites are common rocks on Mars regardless of their sources.  相似文献   

Vertical heat transfer based on direct microstructure measurements in the ice-free Pacific-side Arctic Ocean: the role and impact of the Pacific water intrusion     

Yusuke Kawaguchi  Takashi Kikuchi  Ryuichiro Inoue 《Journal of Oceanography》2014,70(4):343-353

This study quantifies diapycnal mixing and vertical heat transfer in the Pacific side of the Arctic Ocean, where sea-ice cover has disappeared between July and September in the last few decades. We conducted microstructure measurements in the open water region around the Canada Basin from late summer to fall in 2009 and 2010 using R/V Mirai. In the study domain, the dissipation rate of turbulent kinetic energy, ε, is typically as low level as O(10^?10) W kg^?1, resulting in vertical heat diffusivity of O(10^?7) m² s^?1, which is close to the molecular diffusivity of heat, suggesting comparatively little predominance of mechanical turbulent mixing. An exception is the case at the Barrow Canyon, where the strong baroclinic throughflow generates substantial vertical mixing, producing ε > O(10^?7) W kg^?1, because of the shear flow instability. Meanwhile, in the confluence region, where the warm/salty Pacific water and the cold/fresh Arctic basin water encounter, the micro-temperature profiles revealed a localized enhancement in vertical diffusivity of heat, reaching O(10^?5) m² s^?1 or greater. In this region, an intrusion of warm Pacific water creates a horizontally interleaved structure, where the double-diffusive mixing facilitates vertical heat transfer between the intruding Pacific water and the surrounding basin waters.  相似文献   

FDM Simulation of Seismic Waves, Ocean Acoustic Waves, and Tsunamis Based on Tsunami-Coupled Equations of Motion     

Takuto Maeda  Takashi Furumura 《Pure and Applied Geophysics》2013,170(1-2):109-127

We have developed a new, unified modeling technique for the total simulation of seismic waves, ocean acoustic waves, and tsunamis resulting from earthquakes, based on a finite difference method simulation of the 3D equations of motion. Using the equilibrium between the pressure gradient and gravity in these equations, tsunami propagation is naturally incorporated in the simulation based on the equations of motion. The performance of the parallel computation for the newly developed tsunami-coupled equations using a domain partitioning procedure shows a high efficiency coefficient with a large number of CPU cores. The simulation results show how the near-field term associated with seismic waves produced by shallow earthquakes leads to a permanent coseismic deformation of the ground surface, which gives rise to the initial tsunami on the sea surface. Propagation of the tsunami along the sea surface as a gravity wave, and ocean acoustic waves in seawater with high-frequency multiple P-wave reflections between the free surface and sea bottom, are also clearly demonstrated by the present simulations. We find a good agreement in the tsunami waveform between our results and those obtained by other simulations based on an analytical model and the Navier–Stokes equations, demonstrating the effectiveness of the tsunami-coupling simulation model. Based on this simulation, we show that the ratio of the amplitude of ocean acoustic waves to the height of the tsunami, both of which are produced by the earthquake, strongly depends on the rise time of the earthquake rupture. This ratio can be used to obtain a more detailed understanding of the source rupture processes of subduction zone earthquakes, and for implementing an improved tsunami alert system for slow tsunami earthquakes.  相似文献   

Nonlinear sloshing in a floating‐roofed oil storage tank under long‐period seismic ground motion     

Tetsuya Matsui  Takashi Nagaya 《地震工程与结构动力学》2013,42(7):973-991

A hybrid analytical and FEM is proposed to investigate the nonlinear sloshing in a floating‐roofed oil storage tank under long‐period seismic ground motion. The tank is composed of a rigid cylindrical wall and a flat bottom, whereas the floating roof is treated as an elastic plate undergoing large deflection. The contained liquid is assumed to be inviscid and incompressible, and the flow is assumed to be irrotational. The method of analysis is based on representation of the liquid motion by superposing the analytical modes that satisfy the Laplace equation and the rigid wall and bottom boundary conditions. The FEM is then applied to solve the remaining kinematic and dynamic boundary conditions at the moving liquid surface coupled with the nonlinear equation of motion of the floating roof. This requires only the discretization of the liquid surface and the floating roof into finite elements, thus leading to a computationally efficient and accurate method compared with full numerical analysis. As numerical examples to illustrate the applicability of the proposed method, two oil storage tanks with single‐deck type floating roofs damaged during the 2003 Tokachioki earthquake are studied. It is shown that the nonlinear oscillation modes with the circumferential wave numbers 0, 2 and 3 caused by the finite liquid surface elevation as well as the membrane action due to large deflection of the deck produce excessively large stresses in the pontoon, which may cause the catastrophic failure of pontoon followed by the submergence of the roof. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The distribution of total and methylmercury concentrations in soils near the Idrija mercury mine, Slovenia, and the dependence of the mercury concentrations on the chemical composition and organic carbon levels of the soil     

Takashi Tomiyasu  Akito Matsuyama  Ryusuke Imura  Hitoshi Kodamatani  Junko Miyamoto  Yuriko Kono  David Kocman  Jo?e Kotnik  Vesna Fajon  Milena Horvat 《Environmental Earth Sciences》2012,65(4):1309-1322

Although the mining activity of the Idrija mine in Slovenia ceased in 1995, a large amount of mining dregs containing high concentrations of mercury remains in the area. The mining dregs were transported with river flow and deposition along the Idrija River. To estimate the dispersion and change in the chemical form of mercury, a total of 28 soil core samples were taken around the river. The individual core samples were separated into layers for the analysis of their chemical composition, carbon contents, total mercury (T-Hg) and methylmercury (MeHg) concentrations. The chemical composition measured by X-ray fluorescence spectrometry was useful to estimate the dispersion of tailings: the fluvial terrace soil had a chemical composition similar to that of the tailings and could be distinguished clearly from the forest soil. The highest T-Hg concentration, 1,100 mg kg⁻¹, was observed in the fluvial terrace soil near the mine. Although the concentration decreased gradually along with distance from the mine, concentrations higher than 200 mg kg⁻¹ of T-Hg were still observed in the fluvial terrace soil approximately 20 km downstream from the mine. In the vertical distribution of T-Hg in the hillslope soil, a higher value was observed in the upper layers, which suggests the recent atmospheric deposition of mercury. The concentration of MeHg was the lowest at the riverside and higher in the hillslope soil, which was the opposite of the T-Hg distribution. The total organic carbon content tracked similarly with the distribution of MeHg and a linear relation with a significantly high correlation coefficient was obtained. The distinction may be related to the different dispersion process of mercury, and the organic carbon contents may be an important factor for MeHg formation.  相似文献   

Sedimentary organic matter contents and porewater chemistry at upper bathyal depths influenced by the 2011 off the Pacific coast of Tohoku Earthquake and tsunami     

Hidetaka Nomaki  Kazuno Arai  Hisami Suga  Takashi Toyofuku  Masahide Wakita  Takuro Nunoura  Kazumasa Oguri  Takafumi Kasaya  Shuichi Watanabe 《Journal of Oceanography》2016,72(1):99-111

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