Galerkin boundary integral equation method for spontaneous rupture propagation problems: SH-case     

Hiroyuki Goto  Jacobo Bielak 《Geophysical Journal International》2008,172(3):1083-1103

We develop a Galerkin finite element boundary integral equation method (GaBIEM) for spontaneous rupture propagation problems for a planar fault embedded in a homogeneous full 2-D space. A 2-D antiplane rupture propagation problem, with a slip-weakening friction law, is simulated by the GaBIEM. This method allows one to eliminate the strong singularities from the integral representation of the traction, and to separate explicitly the expression for the traction into an instantaneous component; static and time-dependent components with weakly (logarithmic) singular kernels; and a dynamic component and a quasi-static component, with continuous, bounded, kernels. Simulated results throw light into the performance of the GaBIEM and highlight differences with respect to that of the traditional, collocation, boundary integral equation method (BIEM). Both methods converge with a power law with respect to grid size, with different exponents. There is no restriction on the CFL stability number for the GaBIEM since an implicit, unconditionally stable method is used for the time integration. The error of the approximation increases with the time step, as expected, and it can remain below that of the BIEM.  相似文献   

Distribution of boulders at Miyara Bay of Ishigaki Island,Japan: A flow characteristic indicator of tsunami and storm waves     

Kazuhisa Goto  Tetsuya Shinozaki  Koji Minoura  Kiyohiro Okada  Daisuke Sugawara  Fumihiko Imamura 《Island Arc》2010,19(3):412-426

This study investigates the distribution of boulders at Miyara Bay of Ishigaki Island, Japan. These boulders were deposited on a reef flat extending approximately 400–1300 m in width. Most boulders were rectangular to ellipsoidal, without sharp broken edges. They are reef and coral rock fragments estimated as <335 m³ (<633 t). Locally in the bay, the relationship between the boulder weight and position shows that boulders of a given weight have a clear limit on seaward distribution on the reef flat. For example, more than 1, 10, and 100 tons of boulders were deposited, respectively, more than 500, 300, and 100 m from the reef edge. The line is consistent with the possible landward transport limit by maximum storm waves at the Ryukyu Islands, suggesting that the line was formed by the reworking of some boulders by maximally strong storm waves, although we can not exclude the possibility that the line was formed by tsunamis. Furthermore, 68% of boulders at the bay are deposited beyond this line. Therefore, the presence of these boulders at their present positions is difficult to explain solely by storm waves, implying the possible tsunami origin of these boulders. The boulders are characteristically concentrated along the high‐tide line, suggesting the drastic reduction of the tsunami hydraulic force along the line. Previous studies using radiocarbon age dating, as well as our study, imply that at least 69 boulders at Miyara Bay were probably deposited at their present positions by the 1771 Meiwa tsunami, although some of these boulders might have been emplaced and displaced on the reef flat by prior tsunami or storm surges.  相似文献   

A Decade After the 2004 Indian Ocean Tsunami: The Progress in Disaster Preparedness and Future Challenges in Indonesia,Sri Lanka,Thailand and the Maldives     

Anawat Suppasri  Kazuhisa Goto  Abdul Muhari  Prasanthi Ranasinghe  Mahmood Riyaz  Muzailin Affan  Erick Mas  Mari Yasuda  Fumihiko Imamura 《Pure and Applied Geophysics》2015,172(12):3313-3341

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Polarization Calibration of the <Emphasis Type="Italic">Chromospheric Lyman-Alpha SpectroPolarimeter</Emphasis> for a 0.1% Polarization Sensitivity in the VUV Range. Part II: In-Flight Calibration     

G. Giono  R. Ishikawa  N. Narukage  R. Kano  Y. Katsukawa  M. Kubo  S. Ishikawa  T. Bando  H. Hara  Y. Suematsu  A. Winebarger  K. Kobayashi  F. Auchère  J. Trujillo Bueno  S. Tsuneta  T. Shimizu  T. Sakao  J. Cirtain  P. Champey  A. Asensio Ramos  J. Štěpán  L. Belluzzi  R. Manso Sainz  B. De Pontieu  K. Ichimoto  M. Carlsson  R. Casini  M. Goto 《Solar physics》2017,292(4):57

The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding rocket instrument designed to measure for the first time the linear polarization of the hydrogen Lyman-\({\upalpha }\) line (121.6 nm). The instrument was successfully launched on 3 September 2015 and observations were conducted at the solar disc center and close to the limb during the five-minutes flight. In this article, the disc center observations are used to provide an in-flight calibration of the instrument spurious polarization. The derived in-flight spurious polarization is consistent with the spurious polarization levels determined during the pre-flight calibration and a statistical analysis of the polarization fluctuations from solar origin is conducted to ensure a 0.014% precision on the spurious polarization. The combination of the pre-flight and the in-flight polarization calibrations provides a complete picture of the instrument response matrix, and a proper error transfer method is used to confirm the achieved polarization accuracy. As a result, the unprecedented 0.1% polarization accuracy of the instrument in the vacuum ultraviolet is ensured by the polarization calibration.  相似文献   

Spatially resolved spectroscopy of passive spiral galaxies   总被引：1，自引：0，他引：1  

Miho Ishigaki †  Tomotsugu Goto  Hideo Matsuhara 《Monthly notices of the Royal Astronomical Society》2007,382(1):270-278

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Storage-efficient reconstruction framework for planar contours     

Hiroyuki Goto  Yoichi Shimakawa 《地球空间信息科学学报》2017,20(1):14-28

A storage-efficient reconstruction framework for cartographic planar contours is developed. With a smaller number of control points, we aim to calculate the area and perimeter as well as to reconstruct a smooth curve. The input data forms an oriented contour, each control point of which consists of three values: the Cartesian coordinates (x, y) and tangent angle θ. Two types of interpolation methods are developed, one of which is based on an arc spline while the other one is on a cubic Hermite spline. The arc spline-based method reconstructs a G¹ continuous curve, with which the exact area and perimeter can be calculated. The benefit of using the Hermite spline-based method is that it can achieve G² continuity on most control points and can obtain the exact area, whereas the resulting perimeter is approximate. In a numerical experiment for analytically defined curves, more accurate computation of the area and perimeter was achieved with a smaller number of control points. In another experiment using a digital elevation model data, the reconstructed contours were smoother than those by a conventional method.  相似文献   

Impacts of nutrient management and decrease in paddy field area on groundwater nitrate concentration: a case study at the Nasunogahara alluvial fan,Tochigi Prefecture,Japan     

Hiroaki Somura  Akira Goto  Hiroyuki Matsui  Elhassan Ali Musa 《水文研究》2008,22(24):4752-4766

In order to help evaluate the trends in the NO₃-N concentration in groundwater with a view to preventing further degradation in water quality in the future, a distributed groundwater quality model was constructed for the Nasunogahara basin. The best fit for the groundwater table elevations by the flow component of the model was achieved with average mean absolute errors (MAEs) of 0·92 m for the calibration period and 0·83 m for the validation period. Moreover, the best fit for the NO₃-N concentration by the water quality component was achieved with average mean relative errors (MREs) of 29·8% for the calibration period and 30·3% for the validation period. After developing a robust model, various change scenarios were tested; specifically, the effects of effluent load control and a decrease in paddy field area on the NO₃-N concentration in groundwater were predicted. The most intensively farmed area contributed about 40% of the total effluent load because of livestock farming in the basin. When the effluent load from this area was decreased by 50%, the average NO₃-N concentrations at sites S1, S2 and S3 were reduced by about 15%; however, the average concentrations at S4 and S5 were reduced by only 1%. Furthermore, when the total effluent load from the concentrated livestock area was removed completely, the average groundwater NO₃-N concentrations at S1, S2 and S3 were reduced by about 30% as compared with the original calculated results. In contrast, decreasing the area of the paddy fields in the basin did not greatly influence the groundwater NO₃-N concentration. In the case of a 70% reduction in paddy field area, average NO₃-N concentrations increased by about 7% at S1, S2 and S3. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Evaluating salinity damage to crops through satellite data analysis: application to typhoon affected areas of southern Japan     

Kensuke Goto  Takehiro Goto  Jephtha C. Nmor  Kazuo Minematsu  Keinosuke Gotoh 《Natural Hazards》2015,75(3):2815-2828

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The morphology–density relation in the Sloan Digital Sky Survey     

Tomotsugu Goto †  Chisato Yamauchi  Yutaka Fujita  Sadanori Okamura  Maki Sekiguchi  Ian Smail  Mariangela Bernardi  Percy L. Gomez 《Monthly notices of the Royal Astronomical Society》2003,346(2):601-614

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Near-Infrared Colors of the Binary Kuiper Belt Object 1998 WW 31     

Takato  Naruhisa  Fuse  Tetsuharu  Gaessler  Wolfgang  Goto  Miwa  Kanzawa  Tomio  Kobayashi  Naoto  Minowa  Yosuke  Oya  Shin  Pyo  Tae-Soo  Saint-Jacque  D.  Takami  Hideki  Terada  Hiroshi  Hayano  Yutaka  Iye  Masanori  Kamata  Yukiko  Tokunaga  A. T. 《Earth, Moon, and Planets》2003,92(1-4):183-191

We have measured near-infrared colorsof the binary Kuiper Belt object (KBO)1998 WW₃₁ using the Subaru Telescope withadaptive optics. The satellite was detectednear its perigee and apogee(0.18“ and 1.2” apart from the primary).The primary and the satellite have similar H–Kcolors, while the satellite is redder thanthe primary in J–H. Combined with the Rband magnitude previously published byVeillet et al., 2002, the color of the primaryis consistent with that of optically red KBOs. Thesatellite's R-, J-, H-colors suggest thepresence of ～1 μm absorption band dueto rock-forming minerals. If the surface of thesatellite is mainly composed by olivine, thesatellite's albedo is higher value than the canonicallyassumed value of 4%.  相似文献