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1.
Kita-Uebaru natural rock slope failure and its back analysis 总被引：3，自引：2，他引：1
A large landslide occurred in Kita-Uebaru (or Asato) area of Nakagusuku village in Okinawa Island (Japan) on 10 June 2006
after a rainy period of about 9 days. The total rainfall was 126 mm from June 8 till the time of the landslide this period.
This landslide destroyed several buildings and roads, and the total travel distance of the landslide was about 110 m. In this
article, the authors were concerned with the initiation conditions of Kita-Uebaru landslide and post-failure motions of the
landslide body. The observations made in the landslide area, structural geology analyses and outcomes of geotechnical investigations
are described first. Then, possible causes of the landslide are investigated through back analyses using as inputs the geological
structure and the strength properties of planes of discontinuities involved in the sliding processes. The final part of the
article is concerned with the simulation of post-failure motions of the landslide body. The results of the investigations
and back analyses indicate that the failure plane was bi-planar and the heavy torrential rainy period for about 3 days was
the main cause of initiation of the landslide. The mechanical model presented in this article was capable of capturing the
overall features of the landslide body following the initiation of the failure. 相似文献
2.
Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services
Kohei OGAWA Edward VERBREE Sisi ZLATANOVA Naohiko KOHTAKE Yoshiaki OHKAMI 《地球空间信息科学学报》2011,14(2):109-118
Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders. 相似文献
3.
4.
Koji Kameo Makoto Okada Moamen El-Masry Toshio Hisamitsu Saneatsu Saito Hiroomi Nakazato Naohiko Ohkouchi Minoru Ikehara Hisato Yasuda Hiroshi Kitazato Asahiko Taira 《Island Arc》2006,15(3):366-377
Abstract A continuous, well-preserved core was obtained from the Choshi area, on the Pacific side of Japan, to investigate paleoceanographic and paleoclimatic changes around the northwestern Pacific region during the middle Pleistocene. Siliciclastic sequences in the core are divided into five formations – the Obama, Yokone, Kurahashi and Toyosato Formations in the Inubo Group and the Katori Formation, in ascending order. Examination of calcareous nannofossils and magnetic polarities detected four datums in the core sediments of the Inubo Group: the top of Reticulofenestra asanoi , the base of Helicosphaera inversa , the top of Pseudoemiliania lacunosa and the Brunhes–Matuyama boundary. Fourteen marine isotope stages (MIS24–MIS11) were identified in the δ18 O and δ13 C records based on detected datums and the graphic correlation with the standard stack oxygen isotope curve. Magnetic susceptibility and gamma-ray attenuation porosity evaluator density were also measured and low values characterize the glacial intervals. Biogenic sedimentation by primary production may be larger during the glacial periods because of invasions of nutrient-rich northern surface-waters related to the southward shift of the Kuroshio front in the Choshi area. 相似文献
5.
Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services
Kohei Ogawa Edward Verbree Sisi Zlatanova Naohiko Kohtake Yoshiaki Ohkami 《地球空间信息科学学报》2013,16(2):109-118
Location-Based Services (LBS), an emerging new business based on smartphone and mobile networks, are becoming more and more popular. Most of these LBSs, however, only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role. Our specific aim is to solve these issues. This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders. 相似文献
6.
Yoshito Chikaraishi Ryouichi Tanaka Ayumi Tanaka Naohiko Ohkouchi 《Organic Geochemistry》2009,40(5):569-573
Deuterium (D) depletion in phytol relative to ambient water as well as other lipids has been widely observed in various biological and geological samples; however, the mechanism for the depletion remains unknown. We have determined the hydrogen isotopic compositions of phytol and its precursors in cucumber cotyledons and have evaluated the fractionation of hydrogen isotopes during phytol biosynthesis. The hydrogen isotopic compositions of geranylgeraniol, dihydrogeranylgeraniol, tetrahydrogeranylgeraniol and phytol are ?281‰, ?302‰, ?325‰ and ?345‰, respectively. The results suggest that significantly D-depleted hydrogen is incorporated stepwise during hydrogenation of geranylgeraniol to phytol. We conclude that hydrogenation is important in controlling D depletion in phytol. 相似文献
7.
Ömer Aydan Yoshimi Ohta Melih Geniş Naohiko Tokashiki K. Ohkubo 《Rock Mechanics and Rock Engineering》2010,43(6):857-875
Underground structures are well known to be earthquake resistant. However, the recent earthquakes showed that underground structures are also vulnerable to seismic damage. There may be several reasons such as high ground motions and permanent ground movements. This study attempts to describe various forms of damage to underground structures such as tunnels, caverns, natural caves and abandoned mines during major earthquakes. Results of various model tests on shaking table are also presented to show the effect of ground shaking on the response and collapse of underground structures in continuum and discontinuum. Furthermore, some empirical equations are proposed to assess the damage to underground structures, which may be useful for quick assessments of possible damage. 相似文献
8.
Yoshinori Takano Jonathan James Tyler Hisaya Kojima Yusuke Yokoyama Yukiko Tanabe Takaharu Sato Nanako O. Ogawa Naohiko Ohkouchi Manabu Fukui 《Applied Geochemistry》2012
The paleolimnology of two lakes which were isolated as a result of the crustal uplift during the late Holocene along the Soya Coast, Lützow-Holm Bay, East Antarctica were studied. The focus was on temporal variations in the biogeochemical composition of sediment cores recovered from Lake Skallen at Skallen and Lake Oyako at Skarvsnes. Both sets of lake sediments record environmental changes associated with a transition from marine to lacustrine settings, as indicated by analyses of C and N contents, nitrogen isotopic compositions (δ15N), and major element concentrations. Changes in the dominant primary producers during the marine–lacustrine transition (marine diatom to cyanobacteria) at L. Skallen was clearly revealed by biogenic opal-A, diatom assemblages, and molecular signature from denaturing gradient gel electrophoresis (DGGE) with 16S ribosomal RNA (rRNA) gene analysis. Radiocarbon dating of acid-insoluble organic C suggested that the environmental transition from marine to fresh water occurred at 2940 ± 100 cal yr BP at L. Skallen and 1060 ± 90 cal yr BP at L. Oyako. Based on these data, a mean crustal uplift rate of 3.2 mm yr−1 is inferred for the history of marine–lacustrine transition via brackish conditions. The geological setting causing glacio-isostatic uplift was the primary factor in controlling the transition event in sedimentary and biological facies. 相似文献
9.
Hidetaka Nomaki Naohiko Ohkouchi Petra Heinz Hisami Suga Yoshito Chikaraishi Nanako O. Ogawa Kouhei Matsumoto Hiroshi Kitazato 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1488-1503
We conducted an in situ feeding experiment using 13C-labeled unicellular algae in Sagami Bay, Japan (water depth, 1450 m), in order to understand the fate of lipid compounds in phytodetritus at the deep-sea floor. We examined the incorporation of excess 13C into lipid compounds extracted from bulk sediments and benthic foraminiferal cells. 13C-enriched fatty acids derived from 13C-labeled algae were exponentially degraded during 6 days of incubation in the sediment. Subsequent enrichments in 13C in sedimentary n-C15, anteiso-C17, and C17 fatty acids indicated the microbial degradation of algal material and production of bacterial biomass in the sediment. We observed the incorporation of 13C-labeled algal phytol and fatty acids into foraminiferal cells. The compositions of 13C-labeled algal lipids in foraminiferal cells were different from those in the bulk sediments, indicating that foraminiferal feeding and digestion influenced the lipid distribution in the sediments. Furthermore, some sterols in Globobulimina affinis (e.g., 24-ethylcholesta-5,22-dien-3β-ol, 24-ethylcholest-5-en-3β-ol, and 23,24-dimethylcholesta-5,22E-dien-3β-ol) were newly produced via the modification of dietary algal sterols within 4–6 days. In addition to the effects of bacteria, feeding by benthic foraminifera can result in a significant reorganization of the composition of organic matter and influence benthic food webs and carbon cycling at the deep-sea floor. 相似文献
10.
Yusuke Yokoyama Tatsuhiro Naruse Nanako O. Ogawa Ryuji Tada Hiroshi Kitazato Naohiko Ohkouchi 《Global and Planetary Change》2006,54(3-4):239-250
We obtained the high-resolution record of terrestrial biomarkers (C29 and C31 n-alkanes) for the last 26,000 years from Oki Ridge in the south Japan Sea that enabled us to discuss millennial scale climate changes. Our sampling resolution for the biomarker during the major deglaciation period (10–19.5 cal ka BP) is 300 years and for the elemental analyses (total organic carbon and total nitrogen) is as good as ca 200 years. The estimated mass accumulation rate of these molecules during the last glacial period is substantially higher than during the Holocene. They also exhibited two distinct peaks at 17.6 cal ka BP and 11.4 cal ka BP, which are coincident with Heinrich Event 1 and the latest stage of the Younger Dryas, respectively. The unique oceanographic setting of the Japan Sea tends to preferentially preserve organic material of aeolian origin. The nature of our biomarker record in fact suggests a strong aeolian signal, and hence their flux to the Japan Sea potentially reflects the climate conditions of the dust source regions and transport intensity. Our results are consistent with previously reported monsoon variations based on other proxies that is indicative of a strong linkage between North Atlantic climate and Asian monsoon intensity. 相似文献