Sedimentary humic acid and fulvic acid as fluorescent organic materials     

Kohji Hayase  Hiroyuki Tsubota 《Geochimica et cosmochimica acta》1985,49(1):159-163

Fluorescence and absorption spectra of sedimentary humic acid (HA) and fulvic acid (FA), with molecular weights ranging from < 10,000 to >300,000, were measured at 20°C and pH 8. The maximum excitation and emission wavelengths of HA were longer than those of FA, being independent of molecular weight. The excitation and emission maxima can be utilized to differentiate between sedimentary HA and FA. It is suggested that the fluorophors in HA are of a higher molecular weight aromatic groups than those in FA.Smaller molecules were found to have a greater fluorescence than larger ones for sedimentary humic substances and this phenomenon is similar to those obtained for humic substances of terrestrial origin. The absorption coefficient (1/g/cm) of HA decreased, while that of FA increased with the increase in molecular weight. It was shown that fluorescence intensity per weight concentration unit of HA increases and that of FA decreases with increasing absorption coefficient.  相似文献   

Storage-efficient method for generating contours focusing on roundness     

Hiroyuki Goto  Yoichi Shimakawa 《International journal of geographical information science》2016,30(2):200-220

A storage-efficient contour generation method, focusing on planar contours, is developed. Given cartographic elevations on a rectangular lattice, a continuous bivariate function, z = f(x, y), is determined by interpolating the elevation values. Then, we focus on a contour determined by z = constant. The contour curve is partitioned into multiple sections, each of which is exactly or approximately round. Three curvature types are introduced to evaluate the roundness of each section. The area and perimeter of the contour are computed by one-dimensional line integration using Green’s theorem. If the contour is open, it is divided into two curves starting from the same initial point, with the control points advancing in opposite directions. Two types of numerical experiments are performed to validate the effectiveness of the proposed method. One experiment uses an analytically defined elevation function and investigates the number of control points and computation time for a resulting computation error. The second experiment uses actual digital elevation model data of an isolated island in Japan and compares the proposed method with existing ones. Because the algorithm does not require lattice subdivision and the number of control points is drastically reduced, the proposed method is storage efficient.  相似文献   

Recent variations in surface specific humidity in the warm season over Japan     

Hiroyuki Iwasaki 《Theoretical and Applied Climatology》2016,123(3-4):845-858

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Volcanic Activity, Hydrothermal Alteration and Epithermal Gold-Silver Mineralization in the Ryuo Mine Area in the Kitami Metallogenic Province, Hokkaido, Japan   总被引：1，自引：0，他引：1  

Hiroyuki MAEDA 《Resource Geology》1998,48(2):105-116

Abstract: Characterization of Neogene magmatism in the Ryuo mine area in the Kitami metallogenic province was carried out on the basis of K-Ar data for felsic–to–mafic terrestrial extrusive and intrusive volcanism from Late Miocene to Early Pliocene. The Ryuo epithermal gold-silver deposit occurs primarily in the felsic volcaniclastic rocks of the Ikutahara Formation and in Ryuo Rhyolite. The Ryuo mineralization age of 7. 7 – 8. 1 Ma coincides well with the hydrothermal alteration age (7. 7 Ma) of Ryuo Rhyolite hosting ore veins. It is concluded that the Ryuo mineralization was essentially accompanied by felsic volcanic activity during the sedimentation of the Ikutahara Formation, and was closely related both temporally and spatially to the intrusive activity of Ryuo Rhyolite. Hydrothermal alteration related to the epithermal gold-silver mineralization of the Ryuo deposit is primarily characterized by early regional and vein-related alterations, and late steam-heated alteration. Early regional alteration consists of a smectite halo (smectite+pyrite±quartz±opal–CT±mordenite°Clinoptilolite–heulandite series mineral). Early vein-related alteration is primarily marked by potassic alteration. This alteration halo can be subdivided into a K-feldspar halo (quartz+adular–ia+pyrite±illite±interstratified illite/smectite±smectite), an illite halo (quartz+illite + chlorite + pyrite ± interstratified illite/smec–tite±smectite) and an interstratified illite/smectite halo (quartz + interstratified illite/smectite+pyrite±smectite). Late steam-heated alteration characterized by kaolinite or alunite locally overprints the early K-feldspar halo. The style of the Ryuo gold-silver deposit is a low-sulfidation epithermal type. The gold–silver–bearing quartz vein precipitates during boiling of ore fluid. The origin of the ore fluid might be meteoric water. The temperature and sulfur fugacity conditions during precipitation of electrum and acanthite are estimated to be 206°– 238°C and 10^-13.5 – 10^-11.6 atm, respectively.  相似文献   

Mass movements caused by recent tectonic activity: The 1999 Chi-chi earthquake in central Taiwan   总被引：10，自引：0，他引：10  

Wen-Neng Wang  Huei-Long Wu  Hiroyuki Nakamura  Shang-Chih Wu  Shoung Ouyang  Ming-Fang Yu 《Island Arc》2003,12(4):325-334

Abstract The Chi‐chi earthquake (M_S = 7.7), which occurred in September 1999, seriously damaged central Taiwan. Approximately 2 years later (July 2001), the Toraji typhoon brought a heavy rainstorm (650 mm rain/day) and triggered widespread landslides in central Taiwan and parts of eastern Taiwan. Approximately 10 000 Chi‐chi earthquake‐induced landslides and 6000 Toraji typhoon‐related mass movements were delineated in an area of 2400 km² using Satellite Pour l’Observation de la Terre (SPOT; French earth resource satellite) images. The landslide distribution could be closely related to the distribution of peak ground acceleration registered during the Chi‐chi earthquake. The study area was composed of Tertiary sedimentary and metamorphic rocks, whose age and induration increased eastward. The earthquake‐induced landslides were mostly distributed in the region between the Chelungpu Fault and the Lishan Fault to the east, whereas they were few in the region east of the Lishan Fault. The Toraji typhoon in 2001 severely damaged both regions that had been shattered by the Chi‐chi earthquake in 1999. The occurrence of earthquake‐induced landslides can be correlated with epicentral distance, and their occurrence has more influence from the rock type than from the ground motion.  相似文献   

β(Mg0.9, Fe0.1)2SiO4: Single crystal structure,cation distribution,and properties of coordination polyhedra     

Hiroshi Sawamoto  Hiroyuki Horiuchi 《Physics and Chemistry of Minerals》1990,17(4):293-300

The synthesis boundaries of the phase transformation; ++ in (Mg_0.9, Fe_0.1)SiO₄, have been clarified at temperatures to 2000° C and pressures up to 20 GPa in order to synthesize single crystals of high quality. A single crystal of (Mg_0.9, Fe_0.1)₂SiO₄ was grown successfully to a size of 500 m. The crystal structure has been refined from single-crystal X-ray intensities. The ferrous ions prefer M1 and M3 sites to over the larger M2 site. The volume change of all the occupied polyhedra does not contribute to the decrease of total volume in the transformation; rather it tends to increase the bulk volume through the expansion of occupied tetrahedra. The volume reduction in the phase transformations is accounted for by unoccupied polyhedra, with the octahedra contributory 60% and the tetrahedra 40% to the V of the transition. The volume change in the transformation is caused also partly by the volume decrease of MO ₆ (25%), partly the unoccupied tetrahedra (45%) and octahedra (30%).  相似文献   

On the design of a longitudinal motion control system of a fully-submerged hydrofoil craft based on the optimal preview servo system     

Sang-Hyun Kim  Hiroyuki Yamato 《Ocean Engineering》2004,31(13):1637-1653

The current control system of a fully-submerged hydrofoil craft based on optimal feedback control has several problems: it has no good performance of contouring waves and it cannot reduce the effect of wave disturbance. In this paper, we apply the optimal preview servo system to the longitudinal control system of a fully-submerged hydrofoil craft in order to settle the problems of current control system. The control system based on optimal preview servo system is composed of feedback controller and feedforward controller. Also in order to design the control system, the necessary prediction range of future information, the weight function in performance index, the future reference input and wave disturbance are determined. Finally, the validity of the proposed control system in this paper is confirmed by simulation. The simulation results show that the control system has good performance of contouring waves in following seas and is effective to settle the problems of current control system of a fully-submerged hydrofoil craft.  相似文献   

Seasonal Changes in Oceanic pCO2 in the Oyashio Region from Winter to Spring     

Takashi Midorikawa  Sonoki Iwano  Kazuhiro Saito  Hiroyuki Takano  Hitomi Kamiya  Masao Ishii  Hisayuki Y. Inoue 《Journal of Oceanography》2003,59(6):871-882

We observed the partial pressure of oceanic CO₂, pCO₂ ^sea, and related surface properties in the westernmost region of the subarctic North Pacific, seasonally from 1998 to 2001. The pCO₂ ^sea in the Oyashio region showed a large decrease from winter to spring. In winter, pCO₂ ^sea was higher than 400 μatm in the Oyashio region and this region was a source of atmospheric CO₂. In spring, pCO₂ ^sea decreased to extremely low values, less than 200 μatm (minimum, 139 μatm in 2001), around the Oyashio region with low surface salinity and this region turned out to be a strong sink. The spatial variations of pCO₂ ^sea were especially large in spring in this region. The typical Oyashio water with minimal mixing with subtropical warm water was extracted based on the criterion of potential alkalinity. The contribution of main oceanic processes to the changes in pCO₂ ^sea from winter to spring was estimated from the changes in the concentrations of dissolved inorganic carbon and nutrients, total alkalinity, temperature and salinity observed in surface waters in respective years. These quantifications indicated that photosynthesis made the largest contribution to the observed pCO₂ ^sea decreases in all years and its magnitude was variable year by year. These year-to-year differences in spring biological contribution could be linked to those in the development of the density stratification due to the decrease in surface salinity. Thus, the changes in the surface physical structure could induce those in pCO₂ ^sea in the Oyashio region in spring. Furthermore, it is suggested that the direction and magnitude of the air-sea CO₂ flux during this season could be controlled significantly by the onset time of the spring bloom. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Pressure-induced alteration in fatty acid composition of barotolerant deep-sea bacterium     

Kazuo Kamimura  Hiroyuki Fuse  Osamu Takimura  Yukiho Yamaoka  Kouichi Ohwada  Jun Hashimoto 《Journal of Oceanography》1992,48(1):93-104

Barotolerant bacterium was isolated from sediment sample which was obtained from the depth of 4033 m in the Izu-Ogasawara Trench. The physiological property, growth characteristics and fatty acid composition were examined. The strain was a psychrotrophic and barotolerant bacterium, and was identified as species in the genusAlteromonas. The fatty acids of the strain were from C12 to C18. As the growth pressure increased, the portion of unsaturated fatty acid in membrane fraction increased due to an increase in the portion of C171 and C181, while the relative portion of C160 and C161 decreased. On the other hand, as the growth temperature decreased, the portion of unsaturated fatty acid increased due to the increase in the portion of C161 and C181.  相似文献   

III-1 Study on twin-hull-type floating wave energy converter     

Masanori Kobayashi  Hiroyuki Nakagawa 《Ocean Engineering》1985,12(6):566-567

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