著者

松浦 昇 佐々木 孝 鈴山 宏 桑木野 文章 長島 秀樹

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.18, no.2, pp.2_1-2_10, 2006 (Released:2011-06-16)

参考文献数

10

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We developed a prediction method for providing detailed tide level and tidal current information covering the whole Seto Inland Sea.Simulations for 33 days on tide level and the tidal current were carried out after dividing the Seto Inland Sea into the 11 domains. Vertically integrated two-dimensional model was used for the simulation and tide level changes during the target period in the Kii Channel, Bungo Channel, and Kanmon Strait were used as boundary conditions.On the bases of the simulation result, we calculated 29 harmonic constants and constructed the harmonic constant database. The M2 tide and tidal current which are predominant of the Seto Inland Sea were compared with the observation data (48 tide and 51 tidal current stations). As a result, the overall distribution tendency of the M2 tide and tidal current indicated a good reproducibility.Moreover, it was shown that the estimated tidal current of 29 constituents that were acquired from harmonic analysis also reproduced local flows, such as eddies of the downward flow side of the islands, in the Kurushima Strait.Furthermore, good agreements were obtained when compared the tide data of 11 tidal stations in the Seto Inland Sea and the current chart mesh data.This method based on the harmonic analysis of the simulation result can predict the detailed flow of the whole Seto Inland Sea at any time, and the harmonic constant database has high practicality, resulting in a method of wide application.

著者

村上 和男

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.14, no.2, pp.2_1-2_11, 2002 (Released:2012-03-21)

参考文献数

10

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This paper describes the numerical simulation results of tidal current and water exchange in the Seto Inland Sea. Two kinds of computational conditions were prescribed at the open boundary. One is the simple sinusoidal waves of M2 component for Case-1, and another is the composite waves by 28 tidal components for Case-2. Then water exchange computations between the Seto Inland Sea water and Pacific Ocean water were carried out by using the computed flow field of Case-1. In this study, following conclusions are obtained. The computed tidal harmonic constants of M2 component for both cases agree with the observed harmonic constants of M2 component. Around narrow strait, tidal residual flow of Case-2 is larger than that of Case-1 because of the non-linearity of tidal current. The particles thrown into the computed flow field of Case-2 are more dispersed and transported than those of Case-1 by the influence of the non-linearity of tidal current and tidal residual flow. Comparing the computed salinity distribution with the observed salinity distribution, the case of the diffusion coefficient of 500 m2/s gives the most appropriate result. Using these computed flow field and substance dispersion result, the residence time of the Seto Inland Sea is estimated about 200 days.

著者

仙石 新 石田 雄三 杉尾 毅

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.23, no.2, pp.2_1-2_8, 2011 (Released:2011-11-11)

参考文献数

11

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Tidal stream power is renewable energy which is free from hydrocarbon energy source and CO2 emission. In Japan, we have several narrow passages with strong tidal current, more than 10 knots in some cases, and tidal stream power may be utilized in the future, which contributes to reduction of global warming gas. In this paper, we estimate distribution of tidal stream power density in several narrow passages and Setonaikai in Japan from amplitude of M2 and S2 constituents of tidal stream.

著者

浅田 昭 山本 富士夫 徳山 英一 矢島 広樹

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.15, no.1, pp.37-77, 2003-03-31

参考文献数

28

被引用文献数

1

著者

中西 正男

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.23, no.1, pp.1_11-1_23, 2011 (Released:2011-06-06)

参考文献数

23

被引用文献数

1

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Field evaluation of sounding accuracy in the multi-narrow beam echosounder, SeaBeam 2112, on R/V Kairei was carried out in the seafloor with a depth of deeper than 9,000 m. Bathymetric data were gathered while the ship holds on station. Variations of pitch, roll, and heave indicate that the ship was so stable that the motion of the ship except for heading did not affect for soundings. The depth uncertainty in each beam was estimated by forming the ratio of the standard deviation of the soundings in each angular bin to their mean. The soundings in observation range from 8,500 m to 10,900 m. The uncertainty in most beams from beam angle -24° to 27° is below the quality assurance (< 0.5%) demanded by the manufacturer. That of outer beams from the beam angle -24° and 27° is larger than 0.5% because of beam pointing errors by motion of the ship and topographic relief. The uncertainty of all beams at a constant heading was lower than 0.5%. The depth uncertainty near the vertical beam was lower than 0.1%. Soundings by SeaBeam 2112 on R/V Kairei in deeper than 10,900 m of water depth satisfy Order 1b of Standards for Hydrographic Surveys (S-44) by the International Hydrographic Organization.

著者

巻 俊宏 近藤 逸人 浦 環 坂巻 隆 水島 隼人 柳澤 政生

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.21, no.1, pp.1_13-1_25, 2009 (Released:2010-10-18)

参考文献数

14

被引用文献数

2

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The authors have proposed an innovative method to navigate an autonomous underwater vehicle (AUV) for visual mapping of seafloor with high positioning accuracy without using any vision-based matching. The proposed method was implemented in the AUV Tri-Dog 1 and sea experiments were carried out at Tagiri vent field, Kagoshima bay in Japan (Maki et al., 2008). Based on the success of the experiments, a series of dives was carried out at the same place. The AUV Tri-Dog 1 succeeded in 12 fully autonomous dives with a total duration of 29 hours. The vehicle took 9,288 pictures of the seafloor, keeping the altitude of 1.2 m with a surge speed of 0.08 m/s. A photomosaic of the seafloor was created by mapping 7,289 pictures based on the real-time estimates of the AUV state, without any pictorial correlation. The distributions of detailed features such as tube-worm colonies and bacteria mats are clearly shown. The photomosaic covers around 3,000 square meters. To the knowledge of the authors, this is one of the largest underwater photomosaic ever reported. The mapping accuracy was estimated to be 0.3 to 0.8 m based on the comparison of the photomosaic between dives.

著者

村島 崇

出版者

Japan Society for Marine Surveys and Technology

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.16, no.2, pp.31-37, 2004-09-30

著者

巻 俊宏 近藤 逸人 浦 環 坂巻 隆 水島 隼人 柳澤 政生

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.20, no.1, pp.1_1-1_16, 2008

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Although underwater visual observation is an ideal method for detailed survey of seafloors, it is currently a costly process that requires the use of Remotely Operated Vehicles (ROVs) or Human Occupied Vehicles (HOVs), and can cover only a limited area. This paper proposes an innovative method to navigate an autonomous underwater vehicle (AUV) to create both 2D and 3D photo mosaics of seafloors with high positioning accuracy without using any vision-based matching.<br>The vehicle finds vertical pole-like acoustic reflectors to use as positioning landmarks using a profiling sonar based on a SLAM (Simultaneous Localization And Mapping) technique. These reflectors can be either artificial or natural objects, and so the method can be applied to shallow vent fields where conventional acoustic positioning is difficult, since bubble plumes can also be used as landmarks as well as artificial reflectors. Path-planning is performed in real-time based on the positions and types of landmarks so as to navigate safely and stably using landmarks of different types (artificial reflector or bubble plume) found at arbitrary times and locations. Terrain tracker switches control reference between depth and altitude from the seafloor based on a local map of hazardous area created in real-time using onboard perceptual sensors, in order to follow rugged terrains at an altitude of 1 to 2 meters, as this range is ideal for visual observation.<br>The method was implemented in the AUV Tri-Dog 1 and experiments were carried out at Tagiri vent field, Kagoshima Bay in Japan. The AUV succeeded in fully autonomous observation for more than 160 minutes to create a photo mosaic with an area larger than 600 square meters, which revealed the spatial distribution of detailed features such as tube-worm colonies, bubble plumes and bacteria mats. A fine bathymetry of the same area was also created using a light-section ranging system mounted on the vehicle. Finally a 3 D representation of the environment was created by merging the visual and bathymetry data.

著者

伊藤 弘志 植木 俊明 岡村 行信

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.28, no.1, pp.p1-1-P1-6, 2016

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To estimate the scale and feature of earthquake, the location and geometry of faults are important information. Japan Coast Guard conducted the seismic reflection survey in the focal area of the 1964 Niigata Earthquake in order to extract the location and geometry of faults in 2004, but tectonic geomorphological implications were not considered then. In this study the parameters of the multibeam echo sounder were estimated and the location and geometry of faults were extrapolated from the geographic map. They almost corresponded with the distribution of faults evaluated on the seismic reflection profile. More certain structural map was compiled from both results.

著者

徳山 英一 本座 栄一 木村 政昭 倉本 真一 芦 寿一郎 岡村 行信 荒戸 裕之 伊藤 康人 除 垣 日野 亮太 野原 壮 阿部 寛信 坂井 眞一 向山 建二郎

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.13, no.1, pp.27-53, 2001-03-31

参考文献数

56

被引用文献数

6

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We propose the guideline to identify fault in offshore region mainly based on MCS profiles, combining high resolution bathymetric maps and geological data such as bore hole results. Based on the guideline we distinguished total 776 faults developing around Japan since the latest Miocene and 753 faults out of total numbers of faults are interpreted to have been active by Quaternary. Together with distinguishment of fault we examined the attributes of each faults such as surface and vertical distribution, criteria of offset, age of movement, certainty of a fault and so on. <br>The results of the distinguishment and examination of the fault leads to the conclusion that the ongoing tectonic framework around Japan characterized by 1) oblique Subduction along the Nankai Trough, 2) rifting at the Okinawa Trough, 3) E-W compressionl regeme along the Japan Sea margin, 4) E-W compressionl regeme along southwestern margin of the Okhotsk Sea and off southern Hokkaido, 5) E-W compressionl regeme along the Japan Trench, 6) rifting in the central arc of the Izu-Ogasawara Arc has been established since 3 Ma, at the earliest 6 Ma. <br>We utilized high resolution data set which we enable to access. Tow big problems, however, still remain in terms of reliability of fault recognition. Those are 1) age of fault movement and 2) spatial distribution of fault. To solve the first one, new technique is required in order to obtain core samples which provide critical evidence to determine age of fault movement. As is second problem concerned, new intensive seismic survey is indispensable to make a precise fault distribution map, especially in the boundary area between land and sea.

著者

西村 清和 岸本 清行 上嶋 正人 荒井 晃作

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.19, no.1, pp.9-23, 2007-03-31

参考文献数

13

被引用文献数

1

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In the deep-sea geological survey, good survey results are difficult to obtain by a conventional surface-towed acoustic survey system, because the horizontal resolution is limited due to the long distance between the sensor and the target (seafloor). In order to improve the horizontal resolution, a deep-tow system, which tows the sensor in the vicinity of seafloor, is most practical, and many such systems have been developed and used until today. It is not easy, however, to carry out a high-density survey in a small area by maneuvering the towing body altitude sufficiently close to the seafloor with rugged topography. A ROV (Remotely Operated Vehicle) can be used to solve this problem. The ROV makes a high-density 2D survey feasible because of its maneuverability, although a long-distance survey is difficult with it. Accordingly, we have developed an acoustic survey system installed on a ROV. The system named DAIPACK (Deep-sea Acoustic Imaging Package) consists of (1) a deep-sea sub-bottom profiler and (2) a deep-sea sidescan sonar.<br> (1) Deep-sea sub-bottom profiler<br> A light-weight and compact sub-bottom profiler for shallow water was chosen to improve and repackage for the deep sea usage. The system is composed of three units; a transducer, an electronic unit and a notebook computer for system control and data acquisition. The source frequency is 10kHz. To convert the system for the deep sea, the transducer was exchanged for the deep sea model, and the electronic unit was improved accordingly. The electronic unit and the notebook computer were installed in a spherical pressure vessel.<br> (2) Deep-sea sidescan sonar<br> We remodeled a compact shallow sea sidescan sonar(water depth limitation is 30m ) into a deep sea one. This sidescan sonar is composed of a sonar towfish (transducers and an electronic unit ), a cable and a notebook computer (data processor). To accommodate in the deep water, the transducers were remodeled into a high pressure resistance type, and the electronic unit and the computer unit were stored in a spherical pressure vessel. The frequency output of the sidescan sonar is 330kHz, and the ranging distance is variable from 15m to 120m (one side).

著者

土屋 明 新家 富雄

出版者

Japan Society for Marine Surveys and Technology

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.2, no.1, pp.1_45-1_54, 1990

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On this paper, we describe the result in a basic study for a technical developing classification of coastal bottom material by using of acoustic reflection method. As the item of classification of bottom material, we selected, especially, such physical properties as grain size distribution and volume concentration (porosity) of particles in soft-mudsediment. Newly physical parameter <I>CPC</I> (cumulative weight percentage of particle volume concentration) is defined.<br> The other hand, we have derived a new conception of acoustic propagation, sound velocity and attenuation, for a model of N-phase suspension. In the conception, the volume ratio of N-phase particles classified by grain size in modefied suspension is particularly introduced.<br> The applicability of the conception for the soft-mud sediment was verified through both numerical simulations and laboratory experiments measuring physical properties, sound speed and attenuation at several frequencies.<br> A center frequency <I>f</I> of sound speed dispersion has a good response with the mediam grain size φ<SUB><I>m</I></SUB> (φ<SUB><I>m</I></SUB>=-log<SUB>2</SUB> 2 <I>a<SUB>m</SUB></I>; <I>a<SUB>m</SUB></I> is radius of particle in milli-meter) in the <I>CPC</I> curve. Then, the regressive formulation is<br> φ<SUB><I>m</I></SUB>=1.62 <I>F</I>+3.99±0.244<br> where <I>F</I>≡log<SUB>10</SUB> <I>f</I>; <I>f</I> in kHz.<br> A maximum V<SUB>m</SUB> of sound velocity at higher frequency range, eg. several hunderd kilo-hertz to several hundred mega-hertz, etc., is corresponding to the maximum of <I>CPC</I> curve at each volume concentration <I>C<SUB>p</SUB></I>. The theoretical formulation is<br> <I>C<SUB>p</SUB></I>=<I>CPC</I>={1.125 (<I>V<SUB>m</SUB></I>-1)}<SUP>1/2</SUP><br> where <I>V<SUB>m</SUB></I>=|<I>V<SUB>s</SUB></I>/<I>V<SUB>l</SUB></I>|<SUB>max</SUB>.<br> By using these formulas, φ<I><SUB>m</SUB></I> and <I>C<SUB>p</SUB></I> can be predicted from measured <I>F</I> and <I>V<SUB>m</SUB></I>.