Spectroscopic properties of Cr-doped melilite crystals     

Akiko Sugimoto  Yukio Nobe  Takafumi Yamazaki  Yutaka Anzai  Kiyoshi Yamagishi  Yusaburo Segawa  Humihiko Takei 《Physics and Chemistry of Minerals》1997,24(5):326-332

 Four kinds of Cr-droped melilite crystals, Ca₂MgSi₂O₇ (akermanite), CaAl₂SiO₇ (gehlenite), CaGa₂SiO₇ (Ga-gehlenite) and CaGa₂GeO₇ (GaGe-gehlenite), with different sizes of the sites for Cr ions to substitute, were grown in series, using both the CZ and FZ techniques. Although Cr⁴⁺ is regarded as a major species in melilites, the existence of Cr⁶⁺ in gehlenite is also suggested from the change in absorption spectra by annealing, and the dependence of distribution coefficient of Cr ions on growth atmosphere. Spectral peak shifts are not obvious if the host crystal field is altered in melilites, because the local environment of the sites for Cr ion is possibly changed by reforming the packing features of the host lattice. Received February 7, 1996 / Revised, accepted September 20, 1996  相似文献   

Decadal variations in mixed layer salinity in the Kuroshio Extension recirculation gyre region: influence of precipitation during the warm season     

Tomoyuki Kitamura  Toshiya Nakano  Shusaku Sugimoto 《Journal of Oceanography》2016,72(2):167-175

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A Methodology for Predicting the In Situ Size and Shape Distribution of Rock Blocks   总被引：2，自引：0，他引：2  

L. G. Wang  S. Yamashita  F. Sugimoto  C. Pan  G. Tan 《Rock Mechanics and Rock Engineering》2003,36(2):121-142

Summary In block caving, it is important to estimate the cavability of an ore body. This study proposes a new three dimensional (3D) model for predicting the characteristics of ore fragmentation in block caving, which is based on the Monte Carlo simulation technique. In this paper, the following subjects are discussed: sampling methods of discontinuity, 3D modeling algorithms and conceptualization for analyzing the distribution of discontinuities. In addition, the influence of each modeling parameter on the distribution of ore fragmentation was analyzed. The characteristics of ore fragmentation in a Northern China underground copper mine are used as a case study. Based on the methods discussed here, a software system named “MAKEBLOCK” was developed for analyzing the characteristics of discontinuities in an ore body and predicting the size distribution of ore fragments in block caving. The ore fragmentation attained by using this 3D model is in a good agreement with the field fragmentation measurements. Received November 30, 2001; accepted September 19, 2002; Published online February 25, 2003 Acknowledgement Support for this project came primarily from The National Science Foundation of China (approval No. 59704004). We would like to thank professor J. F. Archbald, head of Faculty of Mining Engineering, Queen's University, Canada, for his excellent advice and for checking the technical presentations of this paper. Authors' address: Dr. Liguan Wang, College of Resources and Safety Engineering, Central South University, Hunan, Changsha, China; e-mail: liguan_wang@hotmail.com  相似文献   

Merger of binary globular clusters: Case of unequal masses     

Junichiro Makino  Kazuhide Akiyama  Daiichiro Sugimoto 《Astrophysics and Space Science》1991,185(1):63-78

Merger process of binary globular cluster is discussed for a pair of unequal-mass components. We calculated the case of mass ratio 10.5 by means of anN-body code with 6144 particles in total. We have found the followings. The mass exchange between the components takes place through the Roche-lobe overflow. In the early stages, however, the dynamical evolution is mainly governed by escape of particles from the system. As the particles escape carrying angular momentum with them, the separation between the component cluster shrinks. The time-scale of this shrinkage depends upon the size of the clusters. When a critical separation is reached, the orbital angular momentum is transferred unstably to the spins of the component clusters. This is the process of the synchronization instability which was found in a previous study on binary cluster of equal masses. As a result the component clusters merge into a single cluster. The structures of the mergers are quite similar among different cases except for the central cores which retain their initial central concentrations. In particular, the ellipticity and the rotation curve are quite close each other among models of different initial radii and of different mass ratios.  相似文献   

Origin and decomposition of sinking particulate organic matter in the deep water column inferred from the vertical distributions of its δN, δ and δ     

Takeshi Nakatsuka  Nobuhiko Handa  Naomi Harada  Tatsuhiro Sugimoto  Shigemi Imaizumi 《Deep Sea Research Part I: Oceanographic Research Papers》1997,44(12):1957-1979

Sinking particles were analyzed for their nitrogen isotopic ratio δ¹⁵N) of total particulate nitrogen (PN), stable carbon isotopic ratio (δ¹³C) and radioactive isotopic ratio (δ¹⁴C) of total particulate organic carbon (POC), at three different latitudinal (temperate, subpolar and equatorial) and geomorphological (trench, proximal abyssal plain and distal abyssal plain) sites in the western North Pacific Ocean using year-long time series sediment trap systems, to clarify the common vertical trends of the isotopic signals in deep water columns. Although the δ¹⁵N and δ¹³C values of sinking particulate organic matter (POM) were partly affected by the resuspension of sedimentary POM from the sea floor, especially in the trench, the changes in δ¹⁵N and δ¹³C values owing to the resuspension could be corrected by calculation of the isotopic mass balance from δ¹⁴C of sinking POC. After this correction, common downward decreasing trends in δ¹⁵N and δ¹³C values were obtained in the deep water columns, irrespective of the latitudes and depths. These coincidental isotopic signals between δ¹⁵N and δ¹³C values provide new constraints for the decomposition process of sinking POM, such as the preferential degradation of ¹⁵N- and ¹³C-rich compounds and the successive re-formation of the sinking particles by higher trophic level organisms in the deep water column.  相似文献   

Effects of environmental regulations on heavy metal pollution decline in core sediments from Manila Bay   总被引：2，自引：0，他引：2  

Takahiro Hosono  Chih-Chieh Su  Atsuko Amano 《Marine pollution bulletin》2010,60(5):780-1745

We investigated the high-resolution heavy metal pollution history of Manila Bay using heavy metal concentrations and Pb isotope ratios together with ²¹⁰Pb dating to find out the effects of environmental regulations after the 1990s. Our results suggested that the rate of decline in heavy metal pollution increased dramatically from the end of the 1990s due to stricter environmental regulations, Administrative Order No. 42, being enforced by the Philippines government. The presented data and methodology should form the basis for future monitoring, leading to pollution control, and to the generation of preventive measures at the pollution source for the maintenance of environmental quality in the coastal metropolitan city of Manila. Although this is the first report of a reduction in pollution in Asian developing country, our results suggest that we can expect to find similar signs of pollution decline in other parts of the world as well.  相似文献   

Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): Fast-Scan Single-Dish Mapping     

S. M. White  K. Iwai  N. M. Phillips  R. E. Hills  A. Hirota  P. Yagoubov  G. Siringo  M. Shimojo  T. S. Bastian  A. S. Hales  T. Sawada  S. Asayama  M. Sugimoto  R. G. Marson  W. Kawasaki  E. Muller  T. Nakazato  K. Sugimoto  R. Brajša  I. Skokić  M. Bárta  S. Kim  A. J. Remijan  I. de Gregorio  S. A. Corder  H. S. Hudson  M. Loukitcheva  B. Chen  B. De Pontieu  G. D. Fleishmann  D. E. Gary  A. Kobelski  S. Wedemeyer  Y. Yan 《Solar physics》2017,292(7):88

The Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope has commenced science observations of the Sun starting in late 2016. Since the Sun is much larger than the field of view of individual ALMA dishes, the ALMA interferometer is unable to measure the background level of solar emission when observing the solar disk. The absolute temperature scale is a critical measurement for much of ALMA solar science, including the understanding of energy transfer through the solar atmosphere, the properties of prominences, and the study of shock heating in the chromosphere. In order to provide an absolute temperature scale, ALMA solar observing will take advantage of the remarkable fast-scanning capabilities of the ALMA 12 m dishes to make single-dish maps of the full Sun. This article reports on the results of an extensive commissioning effort to optimize the mapping procedure, and it describes the nature of the resulting data. Amplitude calibration is discussed in detail: a path that uses the two loads in the ALMA calibration system as well as sky measurements is described and applied to commissioning data. Inspection of a large number of single-dish datasets shows significant variation in the resulting temperatures, and based on the temperature distributions, we derive quiet-Sun values at disk center of 7300 K at \(\lambda = 3~\mbox{mm}\) and 5900 K at \(\lambda = 1.3~\mbox{mm}\). These values have statistical uncertainties of about 100 K, but systematic uncertainties in the temperature scale that may be significantly larger. Example images are presented from two periods with very different levels of solar activity. At a resolution of about \(25''\), the 1.3 mm wavelength images show temperatures on the disk that vary over about a 2000 K range. Active regions and plages are among the hotter features, while a large sunspot umbra shows up as a depression, and filament channels are relatively cool. Prominences above the solar limb are a common feature of the single-dish images.  相似文献   

An extreme flood caused by a heavy snowfall over the Indigirka River basin in Northeastern Siberia     

Shunsuke Tei  Tomoki Morozumi  Shin Nagai  Shinya Takano  Atsuko Sugimoto  Ryo Shingubara  Rong Fan  Alexander Fedorov  Tuyara Gavrilyeva  Nikita Tananaev  Trofim Maximov 《水文研究》2020,34(3):522-537

Flooding is one of the greatest disasters that produces strong effects on the ecosystem and livelihoods of the local population. Flood frequency is expected to increase globally making its risk assessment an urgent issue. In spring-summer 2017, an extreme flooding occurred in the Indigirka River lowland of Northeastern Siberia that inundated a large area. In this study, the extent and climatic drivers of the flooding were determined using the results of field observations, satellite images, and climate reanalysis dataset, and its possible effects on the ecosystem were discussed. In 2017, a significant lowland area of around 16,016 km² was covered with water even in July, which was 5,217 km² (around 4% of the total area) greater than the water-covered area in 2015 when usual hydrological condition in the area was observed. The hydrographic signature obtained for the Indigirka River water level in 2017 was unusual. Although the water level rose sharply at the end of May (which was typical for the Arctic region), it did not fall afterwards and even increased again to an annual daily maximum value in the middle of July. The climate reanalysis dataset obtained for the temporal–spatial variations of snow water equivalent, snowmelt, and runoff over the lowland revealed that a large amount of snowmelt runoff in June and July 2017 produced a large water-covered area and unusually high river water levels that lasted until summer. Snow depth from winter to spring was largest in 2017 over the period from 2009 to 2017, and the surface of the lower reach of the lowland was partially covered with snow even in the end of June due to the extreme snowfall that occurred in October 2016. Such unusual hydrological conditions waterlogged most trees over the lowland, which caused serious ecosystem devastation and changes in the material cycle.  相似文献   

Erratum to: Failure characteristics of rainfall-induced shallow landslides in granitic terrains of Shikoku Island of Japan     

Ranjan Kumar Dahal  Shuichi Hasegawa  Atsuko Nonomura  Minoru Yamanaka  Takuro Masuda  Katsuhiro Nishino 《Environmental Geology》2009,56(7):1311-1312

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Seasonal Changes in Submarine Groundwater Discharge and Associated Nutrient Transport into a Tideless Semi-enclosed Embayment (Obama Bay,Japan)     

Ryo Sugimoto  Hisami Honda  Shiho Kobayashi  Yoshitake Takao  Daisuke Tahara  Osamu Tominaga  Makoto Taniguchi 《Estuaries and Coasts》2016,39(1):13-26

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