A comparison between above-water surface and subsurface spectral reflectances collected over inland waters     

Asif M. Bhatti  Donald Rundquist  John Schalles  Luis Ramirez  Seigo Nasu 《国际地球制图》2013,28(2):133-141

The objective of the research was to undertake a quantitative comparison of spectral-reflectance measurements made slightly above the surface of water bodies with the measurements made slightly below the surface. The study is focused on three rivers; two in Georgia, USA and one in Japan. As expected, the differences in reflectance are not constant and vary with the wavelength. The contribution of surface-reflection effects to the surface reflectance measured slightly above the water is both pronounced and highly variable, but although they do alter the magnitude of the upwelling signal, they do not change the general shape of the spectral profiles. The correction of surface-reflection effects by assuming a proportionality factor (ρ) is not considered to be efficient for inland fresh water bodies. For in situ spectroscopy, the recommended approach is to measure upwelling radiance slightly below the water's surface as a means of minimizing extraneous noise. Researchers should be aware of the potential for diminishing the validity of findings because of measurement errors.  相似文献   

A discussion on metallicity effects on the period-luminosity relations of Cepheids and Miras     

Noriyuki Matsunaga 《Astrophysics and Space Science》2012,337(1):93-98

We present an automatic, fast, accurate and robust method of classifying astronomical objects. The Self Organizing Map (SOM) as an unsupervised Artificial Neural Network (ANN) algorithm is used for classification of stellar spectra of stars. The SOM is used to make clusters of different spectral classes of Jacoby, Hunter and Christian (JHC) library. This ANN technique needs no training examples and the stellar spectral data sets are directly fed to the network for the classification. The JHC library contains 161 spectra out of which, 158 spectra are selected for the classification. These 158 spectra are input vectors to the network and mapped into a two dimensional output grid. The input vectors close to each other are mapped into the same or neighboring neurons in the output space. So, the similar objects are making clusters in the output map and making it easy to analyze high dimensional data.  相似文献   

西南日本秋吉带石炭系高山(Ko-yama)灰岩群的褶皱构造     

Noriyuki INADA  Shigeyuki SUZUKI  Keisuke ISHIDA  Shinji YAMASHITA 《地球学报》2012,33(S1):24-24

The study area is located in Kawakami-cho, Okayama Prefecture, which is occupied by Lower Carboniferous to Middle Permian Ko-yama Limestone Group (Yokoyama et al., 1979), Permian Yoshii Group (Sano et al., 1987) and Triassic Nariwa Group (Tera-oka, 1959). The Nariwa Group unconformably covers the Paleozoic successions (Otoh, 1985). These succes-sions belong to the Akiyoshi Belt. The Ko-yama Limestone Group is composed mainly of massive limestone, with basic volcanic rocks, acidic tuff and chert. The group was dated by foraminifer and fusu-linid as Lower Carboniferous to Middle Permian (Yo-koyama et al., 1979).  相似文献   

西南日本秋吉带石炭系高山(Ko-yama)灰岩群的石炭纪(Visean – Moscovian)牙形石序列     

Keisuke ISHIDA  Sigeyuki SUZUKI  Noriyuki INADA  Shinji YAMASHITA 《地球学报》2012,33(S1):25-28

The Carboniferous conodont faunal succession of the lower part of Ko-yama Limestone Group was studied. The confirmed upper Visean–lower Moscovian lithostratigraphy of the group is characterized by the clastic carbonates with common association of the basaltic pyroclastics and some intercalation of spicular chert beds. The faunal succession of Gnathodus semiglaber (upper Visean), Gnathodus praebilineatus – Lochriea multinodosa (upper Visean), Lochriea ziegleri – Gnathodus girtyi girtyi s.l. (lower Serpukhovian), Neoganthodus symmetricus – Idiognathodus primulus (middle – upper Bashkirian), and Idiognathoides convexus – Gondolella clarki (lower Moscovian) faunas, appears in concordance with the lithostratigraphic order. The faunas are correlative with those from the conodont zones of the Hina, Atetsu, Akiyoshi and Omi limestone groups in the Akiyoshi Belt. The Visean/Serpukhovian boundary of the section was recognized by the FAD of Lochriea ziegleri.  相似文献   

Neogene geological history of the Tohoku Island Arc system     

Eiichi Honza  Hideo Kagami  Noriyuki Nasu 《Journal of Oceanography》1977,33(6):297-310

The Pacific-type orogeny in the Tohoku Island Arc is discussed using marine geological and geophysical data from both Pacific and Japan Sea along the Tohoku region. The Tohoku Arc is divided into three belts; inner volcanic and sedimentary belt, intermediate uplifted belt and outer sedimentary trench belt. Thick Neogene sediments which are distinguished in several layers by continuous seismic reflection profiling occur on both sides of the intermediate belt. The dominant structural trend of the Neogene layers is approximately parallel to the coast line and to the axis of the Japan Trench and has a extension of approximately 100 km in each unit on the Pacific side. The trench slope break is an uplifted zone of Neogene layers. The structural trend of the upper continental slope and outer shelf is relative uplift of the landward side. Tilted block movement toward the west is the dominant structural trend on the Japan Sea side. Structural trends which can be seen in both the inner and outer belts may suggest horizontal compressional stress of east to west. Orogenesis and tectogenesis in the Tohoku Arc has been active since early Miocene or latest Oligocene. It may be implied that the Japan Trench was not present during Late Cretaceous to Paleogene, as is suggested by the volcanism of the Tohoku Arc. The basic framework of the present structure was formed during late Miocene to early Pliocene in both the inner and outer belts. Structural movements were reactivated during late Pleistocene.  相似文献   

Biological effect on removal of Th-234, Po-210 and Pb-210 from surface water in Funka Bay,Japan     

Noriyuki Tanaka  Yoichiro Takeda  Shizuo Tsunogai 《Geochimica et cosmochimica acta》1983,47(10):1783-1790

Vertical and temporal variations in the radioactivities of Th-234, Pb-210 and Po-210 were measured at a station in Funka Bay from April 1979 to February 1980. The inventory of Th-234 showed a minimum in early spring, when a spring bloom of phytoplankton was observed, then a steady increase to a maximum value in late summer, just before open sea water invaded the bay and a secondary phytoplankton bloom started. The inventories of Pb-210 and Po-210 also showed minima in early spring. These results suggest that the removal of these nuclides from sea water is accelerated by biological activity. The concentration of Th-234 decreased with depth, but those of Po-210 and Pb-210 were higher in the bottom water in August 1979 when the bay water was strongly stratified. This may be due to the supply of Pb-210 and Po-210 from the bottom. However, if the supply of these nuclides is expected in sediment particles, the concentrations of these nuclides in suspended matter were not sufficient to explain their increments in the bottom water.Residence times of Th, Pb and Po were estimated by applying a non-steady state model to the bay water when the water stayed in and the concentrations of these nuclides were changing. The mean residence time of Th is not significantly different from that of Pb, but is about half of that of Po, although the difference is much smaller than that obtained by applying a steady state model.  相似文献   

Terrestrial organic matter controlling gas hydrate formation in the Nankai Trough accretionary prism, offshore Shikoku, Japan     

Hiroyuki Saito  Noriyuki Suzuki   《Journal of Geochemical Exploration》2007,95(1-3):88

Sediment core samples from Sites 1175, 1176, and 1178, ODP Leg 190, Nankai Trough were analyzed for sedimentary organic matter and inorganic elemental compositions to clarify geochemical conditions for the formation of gas hydrate. Low chloride concentrations and anomalously low core temperature infer the existence of gas hydrate at Site 1178. Trace amounts of gas hydrate are also suggested for Site 1176. Site 1175 does not have any significant evidence of gas hydrate, although all the three sites are within the gas hydrate stability zone. The sediment from Site 1178 is characterized by abundant terrigenous organic matter, older geologic ages, and comparatively higher maturity levels, suggesting high rates of CO₂ generation during diagenesis. The CO₂ generation potential of sediment may be one of the crucial conditions for the formation of gas hydrate.  相似文献   

Risk assessment of water inrush in karst tunnels based on two-class fuzzy comprehensive evaluation method     

Handong Chu  Guangli Xu  Noriyuki Yasufuku  Zhang Yu  Pola Liu  Jifeng Wang 《Arabian Journal of Geosciences》2017,10(7):179

A feasible and accurate method named two-class fuzzy comprehensive evaluation is put forward to assess the risk of water inrush in karst tunnels. In view of regarding tunnel face as the evaluation object, 12 influencing factors of water inrush are selected as the evaluation index system consisting of 4 first-class and 12 second-class indices. Based on fuzzy mathematics theory and expert evaluation method, all the indices are quantitatively graded according to five risk grades. The weights of indices affecting water inrush are rationally distributed by using analytic hierarchy process. Membership functions and weights of indices are utilized to stepwise compute the membership degree of indices corresponding to risk grade, and the principle of maximum membership degree is carried out to discern the risk grade of water inrush. The tunnel faces in seven segments of Qiyueshan tunnel are chosen as the case studies. Evaluation results are derived from the proposed method, and they are generally consistent with the actual results through comparisons. This method provides a cogent way for evaluating the risk of water inrush in karst tunnels.  相似文献   

Non-food-chain transfer of sediment-associated persistent organic pollutants to a marine benthic fish     

Takeo Sakurai  Jun Kobayashi  Yoshitaka Imaizumi  Noriyuki Suzuki 《Marine pollution bulletin》2009,58(7):1072-1077

We investigated the transfer of persistent organic pollutants (POPs) from unspiked bottom sediment to a benthic marine fish, marbled sole (Pleuronectes yokohamae), via non-food-chain pathways, i.e., via sediment particles and water column. One-year-old sole were held for 28 days in an exposure tank with bottom sediment or in a control tank. o,p′-DDE and tri- to penta-chlorobiphenyls were transferred from the sediment to the fish via non-food-chain pathways, as demonstrated by concentrations in the exposed fish at 2.5-30 times the control levels. A model analysis based on first-order kinetic equations indicated that the overall rate constant of transfer of these compounds from sediment to fish was generally lower than that from food (median of ratio, 0.48). It also suggested that relatively high concentrations of the other POPs in the food and the longer times necessary for them to reach a steady state masked any transfer of them from the sediment.  相似文献   

Depth profiles of venusian sinuous rilles and valley networks     

Shoko Oshigami  Noriyuki Namiki 《Icarus》2009,199(2):250-263

More than 200 venusian channels and valleys have been mapped based on analyses of Magellan SAR images. Sinuous rilles are the most abundant channels among six types of venusian channels, and they are widely distributed on Venus. Morphological characteristics of venusian sinuous rilles include sinuous narrowing reaches, source depressions, and length of several 10s to a few 100s of km. This type of channels is known to exist on the Moon and possibly on Mars. Valley networks on Venus often occur in the vicinity of or in connection to sinuous rilles. Cross-sectional morphologies of sinuous rilles and valley networks are of special importance in discussing their formation processes both qualitatively and quantitatively. We reconstructed cross-sectional profiles of 6 sinuous rilles and 2 valley networks using a new radar clinometric method. Reconstructed cross-sections revealed that floors of the channels and valleys are clearly lower than the surrounding plains. This finding implies that the sinuous rilles and the valley networks have erosional origins. Longitudinal depth profiles of the sinuous rilles show distinct decreasing trends toward the termini. Such decreasing trends of depths are qualitatively in agreement with theoretical models and laboratory experiments of thermal erosion. In order to verify this assertion quantitatively, we conduct simple 1-dimensional model calculations under the assumption that both channel-forming lavas and ground substrate are tholeiitic basalt. For initial lava thicknesses in the range 2-6 m, the model calculations yield good matches to the depth profiles. Estimated duration of lava effusion ranges from several months to a few years. These numerical results support thermal erosion of the sinuous rilles but do not necessarily exclude contributions from mechanical erosion processes. Valley networks seem to have formed under a strong structural control in comparison to sinuous rilles. The valleys vary widely in characteristics of the depth profile and flow directions relative to surface slopes. Therefore valley networks appear to have originated from diverse formation mechanisms.  相似文献