Effective time-domain soil-structure interaction analysis based on FFT algorithm with causality condition     

Yasuhiro Hayashi  Hiroshi Katukura 《地震工程与结构动力学》1990,19(5):693-708

We propose an effective and reliable time-domain substructure technique which takes soil-structure interaction effects into account and uses the flexibility coefficients of unbounded soil obtained in the frequency domain. Compared with previous methods, the frequency points to calculate flexibility coefficients, and computational loads in the calculation of time-domain interaction forces, are reduced. In the formulation, we have assumed the flexibility coefficient to be a periodic function, obtained within the bandlimited frequency range, which also includes the predominant frequencies of the structure and incident wave. Then we simulate the periodic flexibility coefficients using discrete impulse responses in the time-domain analyses. However, the real and imaginary parts of the bandlimited flexibility coefficients do not form a Hilbert transform pair; the discrete impulse responses should be modified to be causal for the time-domain analyses. We present various discrete impulse responses which have been obtained from only the real part, only the imaginary part and from both the real and imaginary parts of the frequency-domain flexibility coefficients by FFT with causality conditions. Through a numerical example the relationship between the modified discrete impulse responses and the validity of the time-domain substructure method is presented.  相似文献   

Geology, Wall-rock Alteration and Vein Paragenesis of the Bilimoia Gold Deposit, Kainantu Metallogenic Region, Papua New Guinea     

Joseph Onglo Espi    Ken-Ichiro Hayashi    Kosei Komuro    Hiroyasu Murakami  Yoshimichi Kajiwara 《Resource Geology》2007,57(3):249-268

The Bilimoia deposit (2.23 Mt, 24 g/t Au), located in the eastern Central Mobile Belt of mainland Papua New Guinea, is composed of fault‐hosted, NW–NNW‐trending Irumafimpa–Kora and Judd–Upper Kora Au‐quartz veins hosted by Middle–Late Triassic basement that was metamorphosed to medium‐grade greenschist facies between Middle–Late Triassic and Early–Middle Jurassic. Mineralizing fluids were introduced during crustal thickening, rapid uplift, change of plate motions from oblique to orthogonal compression, active faulting and S₃ and S₄ events in an S₁–S₄ deformation sequence. The Bilimoia deposit is spatially and temporally related to I‐type, early intermediate to felsic and late mafic intrusions emplaced in Late Miocene (9–7 Ma). Hydrothermal alteration and associated mineralization is divided into 10 main paragenetic stages: (1) chlorite–epidote‐selvaged quartz–calcite–specularite vein; (2) local quartz–illite–pyrite alteration; (3) quartz–sericite–mariposite–fuchsite–pyrite wall‐rock alteration that delimits the bounding shears; (4) finely banded, colloform‐, crustiform‐ and cockade‐textured and drusy quartz ± early wolframite ± late adularia; (5) hematite; (6) pyrite; (7) quartz ± amethyst‐base metal sulfides; (8) quartz–chalcopyrite–bornite–Sn and Cu sulfides–Au tellurides and Te ± Bi ± Ag ± Cu ± Pb phases; (9) Fe ± Mn carbonates; and (10) supergene overprint. Fluid inclusions in stage 4 are characterized by low salinity (0.9–5.4 wt% NaCl equivalent), aqueous–carbonic fluids with total homogenization temperatures ranging from 210 to 330°C. Some of the inclusions that homogenized between 285 and 330°C host coexisting liquid‐ and vapor‐rich (including carbonic) phases, suggesting phase separation. Fluid inclusions in quartz intergrown with wolframite have low salinity (0.9–1.2 wt% NaCl equivalent), aqueous–carbonic fluids at 240–260°C, defining the latter’s depositional conditions. The ore fluids were derived from oxidized magmatic source initially contaminated by reduced basement rocks. Wall‐rock alteration and involvement of circulating meteoric waters were dominant during the first three stages and early part of stage 4. Stage 5 hematite was deposited as a result of stage 4 phase separation or entrainment of oxygenated groundwater. Gold is associated with Te‐ and Bi‐bearing minerals and mostly precipitated as gold‐tellurides during stage 8. Gold deposition occurred below 350°C due to a change in the sulfidation and oxidation state of the fluids, depressurization and decreasing temperature and activities of sulfur and tellurium. Bisulfides are considered to be the main Au‐transporting complexes. The Bilimoia deposit has affinities that are similar to many gold systems termed epizonal orogenic and intrusion‐related. The current data allow us to classify the Bilimoia deposit as a fault‐controlled, metamorphic‐hosted, intrusion‐related mesothermal to low sulfidation epithermal quartz–Au–Te–Bi vein system.  相似文献   

Spectral similarity between scalars at very low frequencies in the unstable atmospheric surface layer over the Tibetan plateau   总被引：1，自引：7，他引：1  

Jun Asanuma  Ichiro Tamagawa  Hirohiko Ishikawa  Yaoming Ma  Taiichi Hayashi  Yongqiang Qi  Jiemin Wang 《Boundary-Layer Meteorology》2007,122(1):85-103

Similarity between temperature and water vapour was investigated in the Fourier domain by using their coherency spectra, defined as the correlation coefficient between their Fourier modes, and the relative efficiency of their vertical transport. The class-averaged values of these indices were computed from the turbulence measurements over sparse grasslands on the Tibetan plateau during the intensive observations of GEWEX (Global Energy and Water Experiment) Asian Monsoon Experiment (GAME). It was found that the energy-containing eddies at scales up to 100z (z being height) are characterised by well-maintained similarity between these scalars. The scalars are highly correlated with each other, and their transport efficiencies are almost equal within this scale range. In contrast, similarity was not always maintained at scales larger than 1000z. Detailed analyses showed that this breakdown of similarity occurs occasionally or sporadically, suggesting that it is caused by events whose average return period is not much smaller than the current averaging time, i.e. 30 min. We speculate that entrainment of drier and warmer air at the top of the atmospheric boundary layer caused the scalar dissimilarity at this scale range.  相似文献   

An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials     

Asten  Michael W.  Yong  Alan  Foti  Sebastiano  Hayashi  Koichi  Martin  Antony J.  Stephenson  William J.  Cassidy  John F.  Coleman  Jacie  Nigbor  Robert  Castellaro  Silvia  Chimoto  Kosuke  Cornou  Cécile  Cho  Ikuo  Hayashida  Takumi  Hobiger  Manuel  Kuo  Chun-Hsiang  Macau  Albert  Mercerat  E. Diego  Molnar  Sheri  Pananont  Passakorn  Pilz  Marco  Poovarodom  Nakhorn  Sáez  Esteban  Wathelet  Marc  Yamanaka  Hiroaki  Yokoi  Toshiaki  Zhao  Don 《Journal of Seismology》2022,26(4):757-780

Journal of Seismology - Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site...  相似文献   

Stability of the Courses of the Warm Coastal Currents along the Kyushu Island Suggested by the Population Structure of the Japanese Turban Shell, Turbo (Batillus) Cornutus     

Shigeaki Kojima  Ryoko Segawa  Ikuo Hayashi 《Journal of Oceanography》2000,56(5):601-604

The genetic structure of a population of the Japanese turban shell, Turbo (Batillus) cornutus at Sata-Misaki Point, on the southern coast of Kyushu Island, was determined on the basis of nucleotide sequences of mitochondrial DNA and compared with that of a population of the western coast of Kyushu Island. The significant genetic differentiation between these two populations suggests that the courses of the warm currents along the coast of the Kyushu Island have been relatively stable after the divergence between the two genetically distant groups of the Japanese turban shell, which was estimated to have occurred during some period in Pleistocene.  相似文献   

High-Reflectivity Coatings for a Vacuum Ultraviolet Spectropolarimeter     

Noriyuki Narukage  Masahito Kubo  Ryohko Ishikawa  Shin-nosuke Ishikawa  Yukio Katsukawa  Toshihiko Kobiki  Gabriel Giono  Ryouhei Kano  Takamasa Bando  Saku Tsuneta  Frédéric Auchère  Ken Kobayashi  Amy Winebarger  Jim McCandless  Jianrong Chen  Joanne Choi 《Solar physics》2017,292(3):40

Precise polarization measurements in the vacuum ultraviolet (VUV) region are expected to be a new tool for inferring the magnetic fields in the upper atmosphere of the Sun. High-reflectivity coatings are key elements to achieving high-throughput optics for precise polarization measurements. We fabricated three types of high-reflectivity coatings for a solar spectropolarimeter in the hydrogen Lyman-\(\upalpha \) (Ly\(\upalpha \); 121.567 nm) region and evaluated their performance. The first high-reflectivity mirror coating offers a reflectivity of more than 80 % in Ly\(\upalpha \) optics. The second is a reflective narrow-band filter coating that has a peak reflectivity of 57 % in Ly\(\upalpha \), whereas its reflectivity in the visible light range is lower than 1/10 of the peak reflectivity (\(\sim 5~\%\) on average). This coating can be used to easily realize a visible light rejection system, which is indispensable for a solar telescope, while maintaining high throughput in the Ly\(\upalpha \) line. The third is a high-efficiency reflective polarizing coating that almost exclusively reflects an s-polarized beam at its Brewster angle of 68° with a reflectivity of 55 %. This coating achieves both high polarizing power and high throughput. These coatings contributed to the high-throughput solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP), which was launched on 3 September, 2015.  相似文献   

Geographical and seasonal variations in biomass and estimated production rates of net zooplankton in Yatsushiro Bay, Japan   总被引：1，自引：1，他引：0  

Miwa Hayashi  Shin-ichi Uye 《Journal of Oceanography》2008,64(6):877-889

The biomass and production rate of net zooplankton were studied at eight stations in Yatsushiro Bay, Japan, monthly from May 2002 to April 2003. Based on environmental conditions, the bay was divided into three regions, viz. northern (average depth, salinity and chlorophyll a concentration: 11 m, 31.8 and 6.5 μg l⁻¹, respectively), central (30 m, 32.8 and 3.2 μg l⁻¹, respectively) and southern (43 m, 33.4 and 1.9 μg l⁻¹, respectively). Net zooplankton biomass was high in warm months and low in cold ones, with annual averages of 20.2, 38.8 and 16.4 mg C m⁻³ in the northern, central and southern regions, respectively. Copepods were the most important constituent (>ca. 70% of net zooplankton biomass) in all regions. The northern region was characterized by the dominance of Oithona spp. in summer and Acartia spp. in winter-spring. In the central region, Microsetella norvegica was most pronounced in summer-fall. In both central and southern regions, Calanus sinicus and Eucalanus spp. dominated in winter-spring and fall, respectively. The annual average net zooplankton secondary production rate was 4.4, 7.5 and 3.9 mg C m⁻³d⁻¹ in the northern, central and southern region, respectively. Combining the results from the present study with those from other collaborative works on microzooplankton allowed us to determine the trophic interactions in Yatsushiro Bay. If the secondary producers depend entirely on phytoplankton for food, their daily carbon requirement is equivalent to 12.5, 21.6 and 19.1% of the phytoplankton biomass in the respective regions.  相似文献   

Groundwater flow and storage processes in an inactive rock glacier          下载免费PDF全文

Jordan S. Harrington  Alexandra Mozil  Masaki Hayashi  Laurence R. Bentley 《水文研究》2018,32(20):3070-3088

Groundwater flow through coarse blocky landforms contributes to streamflow in mountain watersheds, yet its role in the alpine hydrologic cycle has received relatively little attention. This study examines the internal structure and hydrogeological characteristics of an inactive rock glacier in the Canadian Rockies using geophysical imaging techniques, analysis of the discharge hydrograph of the spring draining the rock glacier, and chemical and stable isotopic compositions of source waters. The results show that the coarse blocky sediments forming the rock glacier allow the rapid infiltration of snowmelt and rain water to an unconfined aquifer above the bedrock surface. The water flowing through the aquifer is eventually routed via an internal channel parallel to the front of the rock glacier to a spring, which provides baseflow to a headwater stream designated as a critical habitat for an at‐risk cold‐water fish species. Discharge from the rock glacier spring contributes up to 50% of basin streamflow during summer baseflow periods and up to 100% of basin streamflow over winter, despite draining less than 20% of the watershed area. The rock glacier contains patches of ground ice even though it may have been inactive for thousands of years, suggesting the resiliency of the ground thermal regime under a warming climate.  相似文献   

Near-infrared imaging survey of faint companions around young dwarfs in the Pleiades cluster     

Yoichi Itoh  Yumiko Oasa  Hitoshi Funayama  Masahiko Hayashi  Misato Fukagawa  Toshio Hashiguchi  Thayne Currie 《中国天文和天体物理学报》2011,11(3)

We conducted a near-infrared imaging survey of 11 young dwarfs in the Pleiades cluster using the Subaru Telescope and the near-infrared coronagraph imager. We found ten faint point sources,with magnitudes as faint as 20 mag in the K-band,with around seven dwarfs.Comparison with the Spitzer archive images revealed that a pair of the faint sources around V 1171 Tau is very red in infrared wavelengths,which indicates very low-mass young stellar objects.However,the results of our follow-up proper motion measure...  相似文献   

Land-use comparison of depression-focussed groundwater recharge in the Canadian prairies     

Laura R. Morgan  Masaki Hayashi  Edwin E. Cey 《水文研究》2021,35(9):e14379

In the cold semiarid Canadian prairies, groundwater recharge is focussed under numerous topographic depressions, in which snowmelt runoff converges. Agricultural land uses on the uplands surrounding the depressions affect snow accumulation, snowmelt infiltration, evapotranspiration (ET) and soil moisture dynamics, thereby influencing snowmelt runoff and depression-focussed recharge. The objective of this study is to compare the differences in hydrological processes under two common land uses in the Canadian prairies, namely grazed grass and annual crop, and examine how they affect groundwater recharge. A short-term (3 years) paired catchment study was used for detailed observation of hydrological processes in two depressions, supplemented by a longer-term (17 years) data set covering a larger scale to quantify the differences in snowmelt runoff between the two land uses. Compared to the grazed grassland, the cropland had a shorter and more intense period of ET, and root water uptake restricted to the shallower (top 0–80 cm) soil zone. The amount of snowmelt runoff was greater in the grazed grassland primarily due to a higher amount of snow accumulation, which was dictated by differences in topography. This finding was contrary to previous studies in the Canadian prairies that indicated substantially smaller snowmelt runoff in ungrazed grassland, but was consistent with the larger-scale remote sensing results, which showed only a marginal difference between grazed grasslands and croplands. Groundwater recharge rates were estimated using the chloride mass balance method for the present condition using “modern” pore water containing tritium. The rates were similar between the grazed grassland and croplands, implying similarity in snowmelt runoff characteristics. These results suggest that groundwater recharge will continue to be focussed under depressions in the future, though the amount and seasonality of recharge may be influenced by warmer winters.  相似文献